Unit 4- DNA + protein synthesis =) Flashcards
What is a gene ? (1)
a sequence of DNA bases that codes for a polypeptide
What are the 3 characteristics of a genetic code ?
from spec
- universal
- non-overlapping
- degenerate
What is the genome ?
complete set of genes in a cell
What is proteome ?
full range of proteins that a cell is able
to produce
Outline one difference in transcription between eukaryotic and prokaryotic cells.
- P: direct production of mRNA from DNA
- E: production of premRNA– spliced–> mRNA
What is the fixed position occupied by a gene on a DNA molecule called ? (1)
Locus
Describe how a gene is a code for the production of a polypeptide.
Do not include information about transcription or translation in your answer. (3)
- base sequence
- in triplets
- determines seq. of a.a. – primary structure
Define the term exon. (1)
- base seq. coding for polypeptide
Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule. (2)
- condensation
- between phosphate & deoxyribose
- by DNA polymerase
State three differences between DNA in the nucleus
of a plant cell and DNA in a prokaryotic cell. (3)
Plant (EK) vs PK:
1. associated w/ histones vs x
2. linear vs circular
3. introns vs x
4. x plasmids vs plasmids
5. longer vs shorter
Define ‘non-coding base sequences’ and describe where the non-coding multiple repeats are positioned in the genome. (2)
- DNA that does not code for polypeptides/ a.a./ tRNA
- between genes
.
- in introns
- some triplets code for the same a.a.
Describe two differences between the structure of a tRNA molecule and the structure of an mRNA molecule. (2)
tRNA vs mRNA:
1. clover leaf shape vs linear/ has H bonds vs x
2. has a.a. binding site vs x
3. has anticodon vs codon
4. mRNA has ↑ nucleotides
5. diff mRNAs have diff lengths vs all tRNAs are similar/ same length
Describe and explain a difference in the structure of pre-mRNA and mRNA molecules. (2)
- mRNA has fewer nucleotides, x introns
- ∵ spliced
Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation. (3)
- tRNA brings specific a.a. to ribosome
- anticodon on tRNA binds to codon on mRNA
- a.a. joined to each other in condensation (using ATP) (–> peptide bond)
Describe how mRNA is produced from an exposed template strand of DNA.
Do not include DNA helicase or splicing in your answer. (3)
- free RNA nucleotides line up by complmentary base pairing
- RNA polymerase joins them
- by forming phosphodiester bonds
AMY1 is a gene for amylase.
Multiple copies of the AMY1 gene is an adaptation to a high-starch diet.
Use your knowledge of protein synthesis and enzyme action to explain the advantage of this adaptation. (3)
- ↑ transcription ↑ mRNA
- ↑ translation ↑ enzymes
- faster reactions
Define ‘non-coding base sequences’ and describe where the non-coding multiple repeats are postioned in the genome. (2)
- DNA that x code for proteins
- in between genes
Describe the role of ATP in the process of translation in protein synthesis. (2)
- releases energy
- peptide bond formed between a.a.
Give four structural differences between a DNA molecule and an mRNA molecule. (4)
DNA vs mRNA:
1. deoxyribose vs ribose
2. thymine vs uracil
3. long vs short
4. double stranded vs single stranded
5. H bonds vs x H bonds
Suggest one advantage of showing the genetic code as base sequences on mRNA, rather than triplets on DNA. (1)
ribosomes use code on mRNA to assemble polypeptides
Suggest the role of stop mRNA codons. (2)
- stops translation
- detachment of polypeptide chain from ribosome
