Genetic info

Question 1

Gene

Answer 1

a section of DNA that contains a
code for making a polypeptide
and functional RNA

Question 2

locus

Answer 2

the location of a particular gene on a chromosome

Question 3

allele

Answer 3

a different version of the same gene

Question 4

chromosome

Answer 4

threadlike structure
composed of tightly coiled DNA
wrapped around histones (if it
is a eukaryotic cell)

Question 5

homologous chromosome

Answer 5

a pair of chromosomes that have the same genes
therefore, they are the same size

Question 6

eukaryotic DNA

Answer 6

DNA is stored as chromosomes inside the nucleus
linear chromosomes
DNA is tightly coiled and wrapped around proteins called histones

Question 7

prokaryotic DNA

Answer 7

DNA molecules are shorter and circular
DNA is not wound around histones. Instead, it supercoils to fit in the cell

Question 8

codon

Answer 8

3 bases on mRNA that code for an amino acid

Question 9

start codon

Answer 9

3 bases at the start of an mRNA sequence which help to initiate
translation

Question 10

stop codon

Answer 10

3 bases at the end of every gene that do not code for an amino acid
this causes ribosomes to detach
and therefore stops translation

Question 11

genetic code

Answer 11

an amino acid is coded for by 3 DNA bases which are described
as the “triplet code”

Question 12

what is meant by the genetic code is degenerate

Answer 12

each amino acid is coded for by
more than one triplet of bases

Question 13

what is the advantage of the genetic code being degenerate

Answer 13

if a substitution mutation occurs, the new triplet of bases may still code for the same amino acid
therefore the mutation will have
no impact on the final protein
produced

Question 14

what is the advantage of the genetic code being universal

Answer 14

genetic engineering is possible a human gene can be inserted into another organism
e.g human gene for insulin
inserted into bacteria to make
insulin

Question 15

what is the advantage of the genetic code being non-overlapping

Answer 15

if a point mutation occurs, it will only affect one codon and therefore one amino acid

Question 16

triplet code

Answer 16

an amino acid is coded for by 3
bases

Question 17

mutation

Answer 17

a change in the DNA
can be a gene or chromosome
mutation

Question 18

what is meant by the genetic code is universal

Answer 18

the same triplet of bases codes
for the same amino acid in all
organisms

Question 18

what is meant by the genetic code is non-overlapping

Answer 18

each base in a gene is only part of one triplet of bases that
codes for one amino acid therefore each codon is read as a discrete unit

Question 19

introns

Answer 19

non-coding sequence of DNA

Question 20

exons

Answer 20

sequence of DNA that code for amino acids

Question 21

what is splicing

Answer 21

post transcription modification
removing introns

Question 22

genome

Answer 22

the complete set of genes in a cell

Question 23

proteome

Answer 23

The full range of proteins that a
cell is able to produce

Question 24

anticodon

Answer 24

3 bases on the tRNA which are complementary to the codon on mRNA.

Question 25

mRNA structure

Answer 25

single-stranded made up of codons a copy of one gene

Question 26

tRNA structure

Answer 26

single-stranded, folded to create a cloverleaf shape held in place by hydrogen bonds has an anticodon and amino acid binding site

Question 27

mRNA function

Answer 27

a copy of a gene from DNA created in the nucleus, and it then leaves the nucleus to carry the copy of the genetic code of one gene to a ribosome in the cytoplasm

Question 28

tRNA function

Answer 28

a specific amino attaches at the binding site transfers this amino acid to the ribosome to create the polypeptide chain

Question 29

transcription

Answer 29

the first stage in protein synthesis one gene in DNA is copied into mRNA occurs in the nucleus

Question 30

translation

Answer 30

the second stage in protein synthesis the polypeptide chain is created using both the mRNA base sequence and the tRNA occurs on ribosomes in the cytoplasm

Question 31

which enzymes are involved in transcription

Answer 31

DNA helicase RNA polymerase

Question 32

DNA helicase

Answer 32

catalyses the breaking of hydrogen bonds between the two strands of DNA

Question 33

RNA polymerase

Answer 33

joins adjacent RNA nucleotides together forming a phosphodiester bond

Question 34

pre-mRNA

Answer 34

mRNA in eukaryotes that still contain the introns

Question 35

How is pre-mRNA modified

Answer 35

the introns are removed by a protein called a spliceosome this leaves just the exons

Question 36

what is ATP used for in translation

Answer 36

forming the peptide bond between amino acids

Question 37

Compare the DNA in the mitochondria/ chloroplast to prokaryotic DNA

Answer 37

the DNA is similar to prokaryotic DNA, in that it is: short circular not histone bound

Question 38

How does transcription differ between prokaryotes and eukaryotes

Answer 38

Transcription in prokaryotic organisms results in mRNA that requires no modification because prokaryotic DNA does not contain any introns eukaryotic transcription results in pre-mRNA that needs introns removed

Question 39

What is the role of ribosomes in translation

Answer 39

it holds two tRNA molecules to enable peptide bonds to form between the amino acids

Question 40

What is the role of tRNA in translation

Answer 40

it carries a specific amino acid anticodons align opposite complementary codons on the mRNA