p.18
Translation Mechanism
What are the three main steps of the translation elongation cycle?
Aminoacyl-tRNA binding, peptide bond formation, and translocation.
p.6
Transcription Mechanism
What type of nucleotides are matched with the DNA template during transcription?
Free ribonucleoside triphosphates (ATP, CTP, GTP, UTP).
p.10
Post-Transcriptional Modifications
What are the recognized splice sites for introns?
They tend to start with 'GU-' and end with '-AG'.
p.13
Genetic Code Characteristics
What governs the process of translating nucleotide sequences into amino acids?
A set of rules known as the genetic code.
p.13
Genetic Code Characteristics
How is the genetic code read on mRNA?
In groups of three nucleotide bases called codons.
p.1
Transcription Mechanism
What is the process of transcription?
Transcription is the process where information from DNA is used to form mRNA.
p.20
Protein Synthesis Process
Where do polypeptides synthesized by free ribosomes typically remain?
In the cytoplasm or are transported into various organelles.
p.25
Chromosomal Aberrations
What is monosomy?
A condition with only one chromosome, abbreviated as (2N - 1).
p.8
Transcription Mechanism
What sequence is involved in transcription termination in eukaryotes?
The terminator sequence coding for a polyadenylation signal (AAUAAA).
p.24
Chromosomal Aberrations
What happens during deletion in structural aberrations?
It involves the loss of a portion of a chromosome, usually resulting in lethality due to the removal of a set of genes.
p.23
Gene Mutations and Their Effects
What is the result of a nonsense mutation?
The production of a truncated protein that is usually non-functional.
p.23
Chromosomal Aberrations
How does chromosomal aberration affect phenotype?
The effect depends on how the aberration has affected gene sequences and how many genes are affected; it usually has a more significant impact on phenotype.
p.12
Post-Transcriptional Modifications
When is the poly-A tail added to the mRNA transcript?
After the mRNA transcript has been cleaved downstream of the polyadenylation signal (AAUAAA).
p.23
Chromosomal Aberrations
What is a chromosomal aberration?
A mutation involving a change in the structure or number of chromosomes in a cell.
p.28
Genetic Diseases Related to Mutations
How does the HbS molecule compare to the normal HbA molecule in terms of oxygen transport?
HbS is less efficient in carrying oxygen compared to HbA.
p.5
Transcription Mechanism
What is the role of RNA polymerase in transcription initiation?
To position onto the promoter and unwind the DNA double helix.
p.18
Translation Mechanism
Where does the aminoacyl-tRNA bind during translation elongation?
At the A site of the ribosome.
p.1
Post-Transcriptional Modifications
What is the significance of pre-mRNA in eukaryotic cells?
Pre-mRNA undergoes modifications to become mature mRNA before translation.
p.28
Genetic Diseases Related to Mutations
What happens to sickle-shaped red blood cells in the spleen?
They accumulate for destruction, leading to spleen enlargement and possibly death.
What is the outcome of translation?
Information carried in mRNA is translated into a polypeptide.
p.19
Translation Mechanism
What happens when the ribosome reaches a stop codon during translation termination?
The A site accepts a release factor instead of aminoacyl-tRNA.
p.8
Transcription Mechanism
What role do certain proteins play during transcription termination?
They are recruited to cleave the RNA transcript downstream from the polyadenylation signal.
p.19
Translation Mechanism
What is a polyribosome?
A structure formed when multiple ribosomes translate an mRNA simultaneously.
p.28
Genetic Diseases Related to Mutations
What is a consequence of sickle-shaped red blood cells being more fragile?
They haemolyse readily, resulting in anemia.
p.19
Translation Mechanism
What occurs to the ribosomal subunits after translation termination?
They dissociate along with other components of the translation assembly.
p.1
Protein Synthesis Process
What are the roles of DNA and RNA in protein synthesis?
DNA contains the genetic information, while RNA (mRNA, tRNA, rRNA) plays roles in transcription and translation to synthesize polypeptides.
p.24
Chromosomal Aberrations
What is translocation in structural aberrations?
A portion of a chromosome detaches and re-joins at a different point on the same chromosome or with a different chromosome.
p.25
Chromosomal Aberrations
What is aneuploidy?
A condition with a missing or an extra chromosome, resulting in monosomy or trisomy.
p.14
Genetic Code Characteristics
What does it mean that the genetic code is degenerate?
More than one codon can code for the same amino acid.
p.17
Translation Mechanism
How does the initiator tRNA bind to the start codon AUG?
Via complementary base pairing with its anticodon.
p.2
Protein Synthesis Process
What is the Central Dogma of molecular biology?
The process of DNA being transcribed to RNA, which is then translated into protein.
p.25
Chromosomal Aberrations
What is trisomy?
A condition with one extra chromosome, abbreviated as (2N + 1).
p.22
Gene Mutations and Their Effects
What is an addition mutation?
An addition mutation involves the addition of base pairs in the gene sequence, which can cause a frameshift mutation.
p.20
Protein Synthesis Process
What is the initial step in the synthesis of proteins by ribosomes on the rough endoplasmic reticulum?
The polypeptide sequence begins with a short, specific sequence of amino acids known as the signal peptide.
p.22
Gene Mutations and Their Effects
What is the effect of deleting 3 base pairs from a gene sequence?
It results in the loss of an amino acid in the protein.
p.26
Gene Mutations and Their Effects
What mechanism causes gene mutations?
Change in sequence of one or several DNA nucleotides.
p.27
Genetic Diseases Related to Mutations
What is the typical reproductive status of individuals with Down syndrome?
Most are sexually undeveloped and sterile.
p.24
Chromosomal Aberrations
What is a structural aberration in chromosomes?
A change in the structure of chromosomes that can occur in four ways.
p.14
Genetic Code Characteristics
How many codons code for amino acids?
61 of the 64 possible codons code for amino acids.
p.19
Translation Mechanism
What is the advantage of having polyribosomes in a cell?
They enable a cell to make copies of the same polypeptide quickly.
p.17
Translation Mechanism
What is the role of the start codon AUG during translation initiation?
It is positioned at the future P site of the ribosome.
p.27
Genetic Diseases Related to Mutations
What is a karyotype from a male with Down syndrome characterized by?
Characteristic facial features and short stature.
p.9
Post-Transcriptional Modifications
What is added to the 5' end of pre-mRNA during 5’ capping?
A 7-methylguanosine residue.
p.26
Gene Mutations and Their Effects
What is the definition of a gene mutation?
Change in the sequence of a gene found in a particular region of a chromosome.
p.17
Translation Mechanism
What is the role of initiation factors in eukaryotic translation initiation?
They bind to the small subunit to stabilize the structure.
p.2
Transcription Mechanism
What is the difference between transcription initiation in prokaryotes and eukaryotes?
Prokaryotes have a simpler initiation process, while eukaryotes require additional factors and modifications.
p.21
Gene Mutations and Their Effects
What can a change in the mRNA sequence lead to?
A different amino acid sequence in the polypeptide.
p.3
Structure and Roles of DNA and RNA
What is the process of DNA replication?
Preserving information carried in a gene’s DNA sequence for future generations.
p.9
Post-Transcriptional Modifications
What allows mRNA to be immediately used for translation in prokaryotes?
The lack of a nuclear envelope.
p.24
Chromosomal Aberrations
What is duplication in the context of structural aberrations?
It involves the doubling of a portion of a chromosome, leading to repeated sets of genes.
p.20
Translation Mechanism
What processes can occur simultaneously in prokaryotes?
Transcription and translation.
p.12
Post-Transcriptional Modifications
How does the poly-A tail facilitate mRNA export?
It facilitates the export of mature mRNA from the nucleus to the cytoplasm.
p.17
Translation Mechanism
What sequence does the mRNA binding site on the small subunit bind to in prokaryotes?
The Shine-Dalgarno sequence.
What is translation in the context of protein synthesis?
Translation is the process where mRNA is decoded to synthesize polypeptides.
p.20
Protein Synthesis Process
What is the fate of proteins synthesized by ribosomes on the rough endoplasmic reticulum?
They are generally secreted out of the cell, inserted into membranes, or transported into lysosomes.
p.26
Chromosomal Aberrations
What is the definition of chromosomal aberration?
Change in the structure or number of chromosomes.
p.1
Chromosomal Aberrations
What is a chromosomal aberration?
A chromosomal aberration is a structural or numerical alteration in chromosomes.
p.9
Post-Transcriptional Modifications
Why are post-transcriptional modifications absent in prokaryotes?
Because prokaryotes have no introns and lack a nuclear envelope.
p.2
Genetic Code Characteristics
What is the genetic code?
A set of rules that defines how the sequence of nucleotides in DNA or RNA is translated into proteins.
Where does translation occur in prokaryotic cells?
In the cytoplasm (ribosomes).
What is a polyribosome?
A complex of multiple ribosomes translating a single mRNA strand simultaneously.
p.2
Gene Mutations and Their Effects
What is a silent mutation?
A mutation that does not change the amino acid sequence of a protein.
p.4
Transcription Mechanism
What does a transcription unit include?
The gene, its promoter, and terminator sequences.
p.4
Transcription Mechanism
What is the function of the sigma factor in prokaryotic transcription?
It is responsible for recognizing the promoter.
p.19
Translation Mechanism
What does the release factor do during translation termination?
It causes the addition of a water molecule instead of an amino acid to the polypeptide chain.
p.5
Transcription Mechanism
What do general transcription factors recognize and bind to in eukaryotes?
The TATA box at the promoter.
p.5
Transcription Mechanism
What is formed when general transcription factors recruit RNA polymerase?
The transcription initiation complex.
p.17
Translation Mechanism
What is formed during translation initiation?
Translation initiation complex, which includes mRNA, small ribosomal subunit, initiator tRNA, and large ribosomal subunit.
p.13
Genetic Code Characteristics
What are the key features of the genetic code?
It is a triple code, universal, degenerate but not ambiguous, and non-overlapping.
p.6
Transcription Mechanism
What provides the energy for the formation of phosphodiester bonds?
Removal of two phosphates from the incoming ribonucleoside triphosphate.
p.14
Genetic Code Characteristics
What is meant by the genetic code being universal?
The same triplet of bases codes for the same amino acid in all organisms.
p.27
Genetic Diseases Related to Mutations
What are some health issues associated with Down syndrome?
Heart defects, susceptibility to respiratory infections, leukemia, and Alzheimer's disease.
p.14
Genetic Code Characteristics
How many amino acids are coded for by more than one codon?
18 out of 20 amino acids.
p.3
Genetic Code Characteristics
What is a gene?
A specific sequence of DNA nucleotides that codes for a particular polypeptide chain or RNA molecule.
p.14
Genetic Code Characteristics
Give an example of a degenerate codon.
Glycine is coded for by four codons: GGU, GGC, GGA, GGG.
p.3
Protein Synthesis Process
What is the Central Dogma of Molecular Biology?
It describes the unidirectional flow of genetic information from DNA through RNA to polypeptide.
p.26
Chromosomal Aberrations
How many gene loci are involved in chromosomal aberrations?
Involves several gene loci.
p.1
Genetic Diseases Related to Mutations
How can gene mutations lead to diseases?
Gene mutations can alter protein function, leading to diseases like sickle cell anemia.
p.2
Post-Transcriptional Modifications
What is alternative splicing?
A process that allows a single gene to produce multiple protein variants by splicing RNA in different ways.
p.7
Transcription Mechanism
What role do self-complementary sequences play in transcription termination?
Self-complementary sequences in the mRNA form a hairpin loop through complementary base pairing, causing the dissociation of RNA polymerase.
p.22
Gene Mutations and Their Effects
What is a silent mutation?
A silent mutation occurs when a substitution changes the original codon into another codon coding for the same amino acid, resulting in no change to the amino acid sequence.
What are the stages of translation?
Preparation, initiation, elongation, and termination.
p.15
Ribosome Structure and Function
What does the P site of the large ribosomal subunit hold?
The tRNA carrying the growing polypeptide.
p.15
Ribosome Structure and Function
Where are genes coding for ribosomal proteins found in eukaryotic cells?
In the nucleus, outside the nucleolus.
p.16
Translation Mechanism
What is involved in translation preparation?
Attachment of amino acids to tRNA to form aminoacyl-tRNA, catalyzed by aminoacyl-tRNA synthetase.
p.8
Transcription Mechanism
How far downstream from the polyadenylation signal does cleavage occur?
About 10-35 RNA nucleotides.
p.25
Chromosomal Aberrations
What are the two basic types of numerical aberration?
Aneuploidy and polyploidy.
p.18
Translation Mechanism
What catalyzes the formation of peptide bonds during translation?
Peptidyl transferase, which is part of the large ribosomal subunit.
p.9
Post-Transcriptional Modifications
What is the purpose of post-transcriptional modifications?
To form mature mRNA before it leaves the nucleus for translation.
p.18
Translation Mechanism
What is peptidyl transferase classified as?
A ribozyme, an RNA molecule with catalytic function.
p.1
Gene Mutations and Their Effects
What are the types of gene mutations?
Substitution, addition, and deletion, which can lead to changes in the amino acid sequence, including frameshift mutations.
p.7
Transcription Mechanism
What are the similarities between RNA polymerase and DNA polymerase?
Both enzymes synthesize nucleic acids and require a template strand to guide the synthesis process.
p.26
Gene Mutations and Their Effects
How many gene loci are affected by gene mutations?
Affects a single gene locus.
p.1
Chromosomal Aberrations
What is an example of numerical aberration?
Aneuploidy, such as trisomy 21, which causes Down syndrome.
p.25
Chromosomal Aberrations
What are examples of polyploidy?
Triploid (3N), tetraploid (4N), etc.
p.27
Genetic Diseases Related to Mutations
What happens to red blood cells when oxygen levels are low in sickle cell anemia?
HbS molecules precipitate out of solution, causing red blood cells to change to a sickle shape.
p.26
Gene Mutations and Their Effects
What is the severity of gene mutations on phenotype?
May have profound or no effects on the phenotype.
p.22
Gene Mutations and Their Effects
What is a missense mutation?
A missense mutation occurs when a substitution changes the original codon into another codon coding for a different amino acid.
p.16
Ribosome Structure and Function
Where are ribosomal proteins synthesized?
By existing free ribosomes in the cytoplasm.
p.11
Post-Transcriptional Modifications
How does the splicing of α-tropomyosin pre-mRNA differ in various cell types?
Different combinations of exons are spliced together, leading to different mature mRNA sequences and polypeptide sequences.
p.2
Genetic Diseases Related to Mutations
What is sickle cell anemia?
A genetic disease caused by a mutation in the hemoglobin gene, leading to abnormal red blood cells.
p.4
Transcription Mechanism
What is transcription?
The process in which a sequence of bases in the template strand of a gene is copied onto a complementary sequence of bases in RNA (e.g., mRNA).
p.4
Transcription Mechanism
What are the three stages of transcription?
Initiation, elongation, and termination.
p.23
Gene Mutations and Their Effects
What is a nonsense mutation?
A mutation that transforms an original codon into a stop codon (UAG, UAA, or UGA), leading to premature termination of translation.
p.12
Post-Transcriptional Modifications
What is added to the 3' end of eukaryotic pre-mRNA?
A poly-A tail consisting of approximately 200 consecutive adenosine residues.
p.20
Translation Mechanism
What allows translation to be initiated on mRNA before transcription is completed in prokaryotes?
The absence of the nuclear envelope.
p.12
Post-Transcriptional Modifications
What is one function of the 3' poly-A tail?
Protects the mRNA from degradation by hydrolytic enzymes in the cytoplasm.
p.5
Transcription Mechanism
How many types of RNA polymerase are present in prokaryotes?
One type for all kinds of RNA.
p.6
Transcription Mechanism
What happens to the newly formed mRNA transcript during transcription?
It peels away from the DNA.
p.10
Post-Transcriptional Modifications
What is the role of the spliceosome in splicing?
It brings exons close together and facilitates the excision of introns.
p.27
Genetic Diseases Related to Mutations
What is the genetic basis of sickle cell anemia?
It is a homozygous recessive disorder caused by two copies of the defective allele.
p.18
Translation Mechanism
What occurs to the tRNA after translocation?
The free tRNA shifts to the E site and is released, while the peptidyl-tRNA moves to the P site.
p.27
Gene Mutations and Their Effects
What genetic change causes sickle cell anemia?
A single base substitution in the gene coding for the β-globin chain, replacing thymine with adenine.
p.17
Translation Mechanism
What does the small subunit do after binding to the 5' UTR in eukaryotes?
It moves downstream along the mRNA until it reaches the start codon AUG.
p.15
Ribosome Structure and Function
What is the ribosome size in prokaryotes?
70S, with a small subunit of 30S and a large subunit of 50S.
p.27
Gene Mutations and Their Effects
What is the effect of valine replacing glutamic acid in the β-globin chain?
It decreases the solubility of deoxygenated HbS due to valine being hydrophobic.
p.7
Transcription Mechanism
What happens to the newly formed mRNA during transcription termination?
The newly formed mRNA is released, the DNA rewinds, and RNA polymerase dissociates from the DNA.
p.15
Translation Mechanism
How does prokaryotic mRNA bind to the small ribosomal subunit?
Via the Shine-Dalgarno sequence.
p.11
Post-Transcriptional Modifications
How does alternative splicing affect the number of protein products an organism can produce?
It allows for a greater number of different protein products than the number of genes.
p.15
Ribosome Structure and Function
What does the A site of the large ribosomal subunit hold?
The tRNA carrying the next amino acid to be added to the growing polypeptide.
p.11
Post-Transcriptional Modifications
What role does α-tropomyosin play in cells?
It functions in the regulation of contraction.
p.4
Transcription Mechanism
What is the role of the promoter sequence in transcription?
It is the starting site of transcription.
p.24
Chromosomal Aberrations
What occurs during inversion of a chromosome?
A portion of a chromosome detaches and re-joins in an inverted manner, altering the gene sequence but not the overall genotype.
p.20
Protein Synthesis Process
What is the role of the signal peptide in protein synthesis?
It helps the growing polypeptide chain enter the cisternae of the rough endoplasmic reticulum.
p.12
Post-Transcriptional Modifications
What role does the poly-A tail play in mRNA stability?
It stabilizes mRNA as a template for translation.
p.17
Translation Mechanism
What does the initiator tRNA carry in prokaryotes?
Formyl-methionine, a modified form of methionine.
p.7
Transcription Mechanism
What are the main differences between RNA polymerase and DNA polymerase?
RNA polymerase synthesizes RNA from a DNA template, while DNA polymerase synthesizes DNA from a DNA template. Additionally, RNA polymerase does not require a primer, whereas DNA polymerase does.
p.14
Genetic Code Characteristics
What does it mean that the genetic code is not ambiguous?
Each codon only codes for one amino acid.
p.3
Genetic Code Characteristics
What types of RNA do genes in the nucleolus code for?
rRNA, which are not translated into proteins.
p.9
Post-Transcriptional Modifications
What is added to the 3’ end of pre-mRNA during polyadenylation?
A poly-A tail of 50-200 adenine nucleotides.
p.17
Translation Mechanism
What occurs at the completion of the initiation process in both prokaryotes and eukaryotes?
The initiator tRNA sits in the P site of the ribosome, and the vacant A site is ready for the next aminoacyl-tRNA.
p.22
Gene Mutations and Their Effects
How can the function of a protein be affected by the addition or loss of an amino acid?
It may or may not be affected, depending on where the addition or loss occurs on the protein.
p.11
Post-Transcriptional Modifications
What is the process called that allows different polypeptides to be produced from a single gene?
Alternative mRNA splicing.
p.15
Ribosome Structure and Function
What are the three binding sites on the large ribosomal subunit?
Aminoacyl-tRNA site (A site), Peptidyl-tRNA site (P site), and Exit site (E site).
p.21
Gene Mutations and Their Effects
What is the consequence of a frameshift mutation?
It usually produces a non-functional protein.
p.15
Post-Transcriptional Modifications
What modifications do pre-mRNAs undergo to form mature mRNAs?
Post-transcriptional modifications.
p.16
Translation Mechanism
What is amino acid activation?
The synthesis of aminoacyl-tRNA.
p.28
Genetic Diseases Related to Mutations
What complications can arise from sickle-shaped red blood cells obstructing blood vessels?
They can interfere with circulation and deprive organs of oxygen, leading to organ damage.
p.13
Genetic Code Characteristics
Why is the genetic code considered a triplet code?
Each mRNA codon consists of three consecutive nucleotide bases.
p.24
Chromosomal Aberrations
How do structural aberrations affect alleles on chromosomes?
They result in a reshuffling of alleles, which can often be harmful.
p.18
Translation Mechanism
What happens to the tRNA at the P site after peptide bond formation?
It loses its amino acid/peptide.
p.13
Genetic Code Characteristics
Why are three nucleotide bases necessary to code for 20 amino acids?
Four bases can form 64 combinations (4^3), which is sufficient to specify all 20 amino acids.
p.15
Translation Mechanism
What directs the synthesis of polypeptides at the ribosomes during translation?
Information stored in the nucleotide sequence of mRNA.
p.21
Gene Mutations and Their Effects
How does a gene mutation affect mRNA during transcription?
It results in a different mRNA sequence.
p.22
Gene Mutations and Their Effects
What happens when 3 base pairs are added to a gene sequence?
It results in the addition of an extra amino acid in the protein.
p.2
Post-Transcriptional Modifications
What are post-transcriptional modifications in eukaryotes?
5' capping, splicing, and 3' polyadenylation.
p.21
Gene Mutations and Their Effects
What may result from a change in the primary structure of a polypeptide?
An abnormal or non-functional protein.
p.3
Transcription Mechanism
What is the outcome of transcription?
Information carried in a gene is transcribed into RNA (mRNA).
p.21
Gene Mutations and Their Effects
What happens during base pair additions and deletions?
One or more pairs of DNA nucleotides are added or deleted from a gene.
p.11
Post-Transcriptional Modifications
What are alternative exons?
Exons that are not always found in the mature mRNA after splicing.
p.16
Translation Mechanism
What is translation?
The synthesis of a polypeptide under the direction of mRNA.
p.16
Translation Mechanism
What is required for the attachment of amino acids to tRNA?
Energy from ATP hydrolysis.
p.4
Transcription Mechanism
What is the terminator sequence in transcription?
It is where transcription stops.
p.20
Post-Transcriptional Modifications
What happens to the signal peptide after the polypeptide enters the cisternae?
It is cleaved from the polypeptide chain by enzymes.
p.9
Post-Transcriptional Modifications
What is the function of the 5’ cap?
It protects mRNA from degradation, aids in export from the nucleus, and helps mRNA bind to ribosomes.
p.18
Translation Mechanism
What happens to the A site after translocation?
It becomes empty and aligned to the next codon.
p.7
Transcription Mechanism
How is transcription elongation similar to DNA replication elongation?
Both processes involve the addition of nucleotides to a growing strand, using a template to ensure complementary base pairing.
p.25
Chromosomal Aberrations
What is polyploidy?
A condition with more than 2 sets of chromosomes.
p.15
Ribosome Structure and Function
What is the ribosome size in eukaryotes?
80S, with a small subunit of 40S and a large subunit of 60S.
p.26
Chromosomal Aberrations
What are the results of chromosomal aberrations?
Can lead to new genotypes due to reshuffling of alleles and can result in aneuploidy and polyploidy.
p.15
Translation Mechanism
How does eukaryotic mRNA bind to the small ribosomal subunit?
Via the 5' untranslated region (5' UTR).
p.21
Gene Mutations and Their Effects
What is a frameshift mutation?
A mutation that occurs when the number of DNA nucleotides added or deleted is not 3 or multiples of 3, altering the reading frame of mRNA.
p.26
Gene Mutations and Their Effects
Which type of mutation plays a more important role in evolution?
Gene mutations, as they give rise to new alleles in the gene pool for natural selection to operate.
p.26
Genetic Diseases Related to Mutations
What causes Down syndrome?
Failure in the separation of homologous chromosome 21 during anaphase I or II in meiosis, resulting in an abnormal gamete with an extra copy of chromosome 21.
p.24
Genetic Diseases Related to Mutations
What is an example of a disease caused by translocation?
A form of leukemia due to the translocation of chromosome 22 to chromosome 9.
p.25
Chromosomal Aberrations
What is an example of monosomy?
Monosomy X, resulting in Turner’s syndrome.
p.21
Gene Mutations and Their Effects
What is a gene mutation?
A change in the DNA sequence of a gene.
p.20
Protein Synthesis Process
How do polypeptides synthesized by ribosomes on the rough endoplasmic reticulum fold?
They enter the cisternae and fold into their specific shape.
p.15
Ribosome Structure and Function
What are the two components that make up a ribosome?
A small ribosomal subunit and a large ribosomal subunit.
p.27
Gene Mutations and Their Effects
How does the mutation in sickle cell anemia affect the mRNA codon?
It changes the codon from GAG (coding for glutamic acid) to GUG (coding for valine).
p.14
Translation Mechanism
In which direction is mRNA read during translation?
In the 5’ to 3’ direction.
p.21
Gene Mutations and Their Effects
What are the two general categories of mutations within a gene?
Base pair additions and deletions, and base pair substitutions.
p.2
Ribosome Structure and Function
What are the components of ribosomes?
Small and large ribosomal subunits.
p.11
Post-Transcriptional Modifications
What are constitutive exons?
Exons that are always found in the mature mRNA from all cell types.
p.2
Gene Mutations and Their Effects
What are gene mutations?
Changes in the nucleotide sequence of a gene, which can include additions, deletions, and substitutions.
p.11
Post-Transcriptional Modifications
How can different polypeptide sequences affect α-tropomyosin?
They may alter its function to meet the needs of particular cell types.
p.16
Translation Mechanism
Where does the amino acid bind on the tRNA?
At the amino acid binding site at the 3’ end.
p.4
Transcription Mechanism
What is the non-template strand also known as?
The non-template/sense/coding strand.
p.1
Gene Mutations and Their Effects
What is a gene mutation?
A gene mutation is a change in the DNA sequence that can affect the amino acid sequence of a protein.
p.17
Translation Mechanism
What happens when the large subunit binds during translation initiation?
It forms the translation initiation complex with hydrolysis of GTP.
p.2
Transcription Mechanism
What are the stages of transcription?
Initiation, elongation, and termination.
p.25
Chromosomal Aberrations
What is an example of trisomy?
Trisomy 21, resulting in Down syndrome.
p.18
Translation Mechanism
What is added to the growing polypeptide chain during elongation?
One amino acid for each codon read.
p.7
Transcription Mechanism
What triggers transcription termination in prokaryotes?
Transcription termination occurs when RNA polymerase reaches the terminator sequence at the end of the transcription unit.
p.11
Post-Transcriptional Modifications
What is one benefit of having both exons and introns in genes?
It enables a single gene to encode more than one type of polypeptide.
p.22
Gene Mutations and Their Effects
What is a substitution mutation?
A substitution mutation occurs when one pair of nucleotides is replaced with another pair.
p.26
Chromosomal Aberrations
What is the severity of chromosomal aberrations on phenotype?
Result in profound effects on the phenotype as many gene loci are involved.
p.22
Gene Mutations and Their Effects
How can a missense mutation affect protein function?
It can significantly affect protein function if the new amino acid has different properties, is important for 3D conformation, or is found in functionally important parts of the protein.
p.16
Ribosome Structure and Function
What is the role of nuclear pores in ribosomal protein synthesis?
They allow ribosomal proteins to enter the nucleus and nucleolus.
p.2
Genetic Diseases Related to Mutations
What is Down syndrome?
A genetic disorder caused by the presence of an extra chromosome 21.
p.16
Translation Mechanism
How many aminoacyl-tRNA synthetases are there?
20, one specific for each amino acid.
p.4
Transcription Mechanism
Which strand of DNA serves as the template for transcription?
The template strand (also called the antisense or non-coding strand).
p.4
Transcription Mechanism
What happens after the synthesis of about 10 nucleotides of mRNA in prokaryotic transcription?
The sigma factor is released, allowing RNA polymerase to move forward and continue transcription.
p.21
Gene Mutations and Their Effects
How can gene mutations affect an organism?
They may affect the phenotype and can lead to heritable diseases.
p.2
Genetic Code Characteristics
What are the characteristics of the genetic code?
It is triplet, universal, degenerate but not ambiguous, and non-overlapping.
p.11
Post-Transcriptional Modifications
What is alternative mRNA splicing?
The conversion of one type of pre-mRNA into more than one type of mature mRNA by retaining and splicing only certain exons.
p.16
Ribosome Structure and Function
What forms ribosomal subunits?
Ribosomal proteins complexed with rRNAs in the nucleolus.
p.4
Transcription Mechanism
How does RNA polymerase recognize the template strand?
By the presence of the specific promoter sequence.
p.15
Ribosome Structure and Function
What happens to genes coding for rRNAs in eukaryotic cells?
They are transcribed in the nucleolus and remain there after synthesis.
p.16
Translation Mechanism
How many stages are there in translation?
Four stages: preparation, initiation, elongation, and termination.
