DNA, RNA and protein synthesis

Question 1

DNA in eukaryotic cells

Answer 1

linear DNA molecules that exist as chromosomes, really long (so wound up, around proteins called histones - which also help support the DNA)

Question 2

DNA in prokaryotic cells

Answer 2

shorter, circular, isn’t wound around histones, it is supercoiled

Question 3

what does a gene code for

Answer 3

polypeptide or functional RNA

Question 4

what is a genome

Answer 4

complete set of genes in a cell

Question 5

what is a proteome

Answer 5

full range of proteins that the cell is able to produce

Question 6

what is functional RNA

Answer 6

RNA that perform special tasks during proteinsynthesis

Question 7

how is an amino acid coded for

Answer 7

sequence of 3 bases called a triplet

Question 8

what is removed during protein synthesis

Answer 8

introns

Question 9

what is an allele

Answer 9

different versions of the same gene that code for different versions of the same polypeptide

Question 10

how many pairs of chromosomes do human cells have

Answer 10

23

Question 11

what is a homologous pair

Answer 11

pairs of matching chromosomes (same size, same genes but could have different alleles)

Question 12

types of RNA

Answer 12

messenger RNA (mRNA) 
transfer RNA (tRNA)

Question 13

messenger RNA

Answer 13

made during transcription, carries genetic code from DNA to ribosomes (where its used to make a protein during proteinsynthesis), single polnucleotide strand, groups of 3 bases = codons/triplets

Question 14

transfer RNA

Answer 14

involved in translation, carries amino acid used to make proteins to the ribosomes, clover shape due to hydrogen bonds between base pairs, amino acid binds to one end, anticodon at one end (specific sequence of tree bases)

Question 15

what is the first stage of protein synthesis

Answer 15

transcription

Question 16

what is transcription

Answer 16

making an mRNA copy of a gene from DNA

Question 17

where does transcription take place in eukaryotic cells

Answer 17

nucleus

Question 18

where does transcription take place in prokaryotic cells

Answer 18

cytoplasm (as they do not have a nucleus)

Question 19

stages of transcription

Answer 19

1) RNA polymerase attaches to the DNA double-helix at the beginning of a gene, and breaks the hydrogen bonds between the genes
2) this causes the strands to seperate and uncoil, exposing some of the bases and the acts as a template to make an mRNA copy from
3) RNA polymerase lines up free RNA nucleotides alongside the exposed bases and complementary base pairing takes place, meaning an mRNA strand of complementary pairing is made
5) the free RNA nucleotides are joined by

Question 20

when does transcription stop?

Answer 20

when RNA polymerase reaches a ‘stop’ codon, it stops making RNA and detaches from DNA

Question 21

how does mRNA move out of eukaryotic cells

Answer 21

moves through the nuclear pore and attaches to a ribosome in the cytoplasm

Question 22

what form of mRNA contains introns and exons

Answer 22

pre-mRNA (in eukaryotic cells)

Question 23

what is removed during splicing

Answer 23

introns

Question 24

what process removes introns

Answer 24

splicing

Question 25

what cells mRNA doesn't contain introns

Answer 25

prokaryotic

Question 26

what is the next stage of protein synthesis

Answer 26

translation

Question 27

what is translation

Answer 27

when amino acids are joined together to make a polypeptide chain, following the sequence of codons carried by the mRNA

Question 28

where does translation occur

Answer 28

at the ribosomes in the cytoplasm

Question 29

what happens during translation

Answer 29

1) mRNA attaches itself to a ribosome , and tRNA molecules carry amino acids to it.. ATP provides the energy required to form the bonds between the tRNA and amino acids 2) a tRNA molecule (carrying an amino acid) with an anticodon complimentary to the first codon of the mRNA attaches to the mRNA by specific base pairing 3) a second tRNA molecule attaches to the next codon in the same way 4) the 2 amino acids on the tRNA molecules are joined by a peptide bond, and the first tRNA molecule moves away leaving behind the amino acid 5) this process continues to produce a chain of linked amino acids, until theres a stop signal on the mRNA chain 6) the polypeptide chain moves away from the ribosome and translation is complete

Question 30

what is the genetic code

Answer 30

sequence of base triplets in mRNA that code for a specific amino acid

Question 31

genetic code features

Answer 31

non-overlapping, degenerate, universal

Question 32

base triplets function

Answer 32

each triplet is read in sequence, they are seperate, and don't share their features

Question 33

what does degenerate mean

Answer 33

there are more possible combinations of triplets than there are amino acids - 20 amino acids, 64 possible triplets - which means some amino acids are coded for by more than one base triplet

Question 34

start and stop codons

Answer 34

code for the start and stop of the production of the protein, found at the beginning and end of the mRNA

Question 35

what does universal mean

Answer 35

same specific base triplets code for the same amino acids in all living things