DNA, genes and protein synthesis

Question 1

What is a gene?

Answer 1

Section of DNA coding for an amino acid sequence/ polypeptide or functional RNA

Question 2

How many bases code for an amino acid?

Answer 2

3

Question 3

What doe the code being degenerate mean?

Answer 3

Many triplet codes can code for the same amino acid

Question 4

What is the start code always coding for?

Answer 4

methionine

Question 5

What do the last 3 triplets form?

Answer 5

Stop code

Question 6

What are 3 properties of DNA?

Answer 6

Non overlapping, degenerate and universal

Question 7

What are coding sequences called?

Answer 7

exons

Question 8

What are non coding sequences called?

Answer 8

introns

Question 9

What type of cells are introns present in?

Answer 9

Eukaryote

Question 10

What do some of the introns code for?

Answer 10

Ribosomal and transfer rna

Question 11

What is prokaryotic DNA like?

Answer 11

Short, circular, not associated with proteins so no chromosomes

Question 12

What us eukaryotic DNA like?

Answer 12

Longer, line, associated with proteins called histones and in chromosomes

Question 13

What is mitochondria and chloroplasts DNA like?

Answer 13

Prokaryotes DNA

Question 14

When are chromosomes visible?

Answer 14

In cell division

Question 15

What are chromosomes made up of?

Answer 15

two chromatids and a centromere

Question 16

What are homologous chromosomes?

Answer 16

Chromosomes with a diploid number where half the DNA is from the mother and half from the father that carry the same gene but not necessarily the same allele

Question 17

What is an allele?

Answer 17

One of a number of alternative forms of a gene

Question 18

What leads to mutations?

Answer 18

Changes in the base sequence of a gene which produces a new allele

Question 19

Why are mutations often bad?

Answer 19

New polypeptide chain makes a protein which may not fit substrate so can’t perform it’s function

Question 20

What happens when each part of the DNA is read?

Answer 20

Transcribed into messenger RNA

Question 21

What is a codon on mRNA?

Answer 21

sequence of 3 bases that codes for an amino acid

Question 22

What is a genome?

Answer 22

Complete set of genes including mitochondria and chloroplasts DNA

Question 23

What is the proteome?

Answer 23

Full range of proteins produced by the genome

Question 24

What structure is RNA?

Answer 24

Single strand

Question 25

What makes up an RNA nucleotide?

Answer 25

Ribose, phosphate and either A,U,C or G base

Question 26

What are the two main types of RNA?

Answer 26

messenger RNA and Transfer RNA

Question 27

Is tRNA or mRNA more stable?

Answer 27

mRNA

Question 28

How long is mRNA and what are the bases determined by?

Answer 28

1000s of nucleotides the bases are determined by bases on DNA during transcription

Question 29

Where does mRNA go?

Answer 29

It leaves the nucleus enters cytoplasm and associates with the ribosomes and acts as a template strand for protein synthesis

Question 30

How is information arranged in mRNA?

Answer 30

In codons where 3 bases are complementary to the bases in DNA and the codons code for a amino acid which determines the sequence.

Question 31

What is the shape of tRNA

Answer 31

Single strand folded into a clover shape where one end extends so specific amino acid can attatch and other end 3 bases make up the anticodon.

Question 32

What are the two main stages of protein synthesis?

Answer 32

Transcription and translation

Question 33

What happens first in transcription?

Answer 33

Part of DNA molecule unwinds and unzips due to hydrogen bonds being broken between bases which is catalysed by DNA helicase

Question 34

What happens after DNA has been unwinded in transcription?

Answer 34

RNA polymerase catalyses the addition of free nucleotides which complementary base pair to form pre mRNA molecules

Question 35

How is it ensured that the molecule remains stable?

Answer 35

DNA strand joins on after so only 12 nucleotides are ever exposed at once.

Question 36

What happens in translation in eukaryotes which doesn't in prokaryotes?

Answer 36

Splicing where introns are removed

Question 37

What happens first in translation?

Answer 37

mRNA is passed out the nuclear pore and a ribosome attaches to the start codon of and the complementary anticodon carries a specific amino acid

Question 38

What happens to the two tRNA amino acids in translation?

Answer 38

Joined by a peptide bond using an enzyme and ATP

Question 39

What happens once the 3rd amino acid is joined?

Answer 39

1st tRNA molecule can leave and can collect another amino acid from the cytoplasm

Question 40

When does the polypeptide chain stop growing?

Answer 40

When it reaches the stop codon

Question 41

What is a polysome system?

Answer 41

When a number of ribosomes combine

Question 42

How is the protein assembled at the end of protein synthesis?

Answer 42

Polypeptide is coiled or folded producing a secondary structure which is folded again to give the tertiary structure and different polypeptide chains along with non protein groups link to form tertiary structure