d1.2 protein synthesis Flashcards
(24 cards)
What is transcription?
The process of synthesizing RNA using a DNA template.
What are the roles of RNA polymerase in transcription?
- Unwinds DNA.
- Reads the antisense strand.
- Synthesizes complementary RNA.
What complementary base pairing occurs during transcription?
- A (DNA) → U (RNA)
- T (DNA) → A (RNA)
- G (DNA) → C (RNA)
- C (DNA) → G (RNA)
What is the difference between the sense and antisense strands of DNA?
- Sense strand matches the RNA sequence.
- Antisense strand serves as the template for RNA synthesis.
How is the stability of DNA maintained?
- Hydrogen bonds between base pairs.
- Double-helix structure.
- Protective histones in eukaryotic cells.
What is gene expression?
The process of converting genetic information into functional proteins.
What are the major steps of gene expression?
- Transcription: DNA → RNA
- Translation: RNA → Protein
How does gene expression determine cell differentiation?
Gene expression regulates which proteins are produced, allowing cells to specialize for different functions.
What is translation?
The synthesis of polypeptides from mRNA.
Where does translation occur in the cell?
On ribosomes in the cytoplasm or rough ER.
What is the role of mRNA in translation?
Carries the genetic code from DNA to ribosomes.
What is the role of ribosomes in translation?
Facilitate the assembly of amino acids into a polypeptide chain.
What is the role of tRNA in translation?
Delivers amino acids to the ribosome based on the mRNA codon sequence.
What complementary base pairing occurs during translation?
The codon (mRNA) pairs with the anticodon (tRNA) through hydrogen bonds.
What is the difference between a codon and an anticodon?
- Codon: A triplet of mRNA bases that codes for an amino acid.
- Anticodon: A triplet on tRNA that is complementary to a codon.
Why does a triplet of nucleotides code for amino acids?
Three nucleotides provide 64 possible combinations, enough to code for 20 amino acids.
What does it mean that the genetic code is degenerate?
More than one codon can code for the same amino acid.
What does it mean that the genetic code is universal?
The same genetic code is used by nearly all organisms.
How do you determine an amino acid sequence from an RNA sequence?
Use a genetic code table to match mRNA codons to amino acids.
What are the major steps of translation elongation?
- Codon recognition – tRNA binds to mRNA codon.
- Bond formation – Peptide bond forms between amino acids.
- Translocation – Ribosome moves along mRNA to the next codon.
What is a gene mutation?
A change in the DNA sequence that may alter protein structure and function.
What causes sickle cell anemia?
A mutation in the HbS allele replacing glutamic acid (Glu) with valine (Val) in hemoglobin.
How does the sickle cell mutation affect hemoglobin?
Distorts the shape of hemoglobin, leading to sickled red blood cells.
What are common symptoms of sickle cell disease?
- Anemia
- Pain crises
- Blocked capillaries
