DNA genes and chromosomes

Question 1

what is the difference between a chromosome and chromatid

Answer 1

chromatids are half of a chromosome
they contain the same genetic material

Question 2

what is a homologous chromosome

Answer 2

chromosome pairs with the same centromere position one from mother and one from father
but they are genetically different

Question 3

describe how DNA is wound into a chromosome

Answer 3

DNA double helix is wound around a histone and the complex then coils.
this coil is further coiled and packaged into a chromosome.

Question 4

what is the haploid number

Answer 4

23

Question 5

what is the diploid number

Answer 5

46

Question 6

what is an allele

Answer 6

version of a gene

Question 7

what is a phenotype

Answer 7

physical expression of a gene

Question 8

what is a genotype

Answer 8

genes you contain

Question 9

why do we have a triplet code

Answer 9

so that we have enough combinations to code for each amino acid

Question 10

what is a locus

Answer 10

the place a particular section of DNA is located

Question 11

what does the base sequence of each gene contain

Answer 11

amino acid sequence in a polypeptide
functional RNA , ribosomal RNA and transfer RNA

Question 12

what is an intron

Answer 12

non coding DNA

Question 13

what is an exon

Answer 13

coding DNA

Question 14

what are the bonds between base pairs

Answer 14

hydrogen

Question 15

what are the bonds between base pairs and backbone

Answer 15

phosphodiester

Question 16

what are the bonds between amino acids

Answer 16

peptide bonds

Question 17

where are triplet codes found

Answer 17

DNA

Question 18

where are codons found

Answer 18

MRNA

Question 19

where are anticodons found

Answer 19

TRNA / proteins

Question 20

what does degenerate mean

Answer 20

amino acids have more than one triplet code

Question 21

what does universal mean

Answer 21

the same triplet of DNA bases are for the same amino acids in all organisums

Question 22

what does non overlapping mean

Answer 22

each DNA base in each triplet is only read once

Question 23

what do genes code for

Answer 23

ribosomal RNA and transfer RNA

Question 24

are introns and exons found in prokaryotic cells

Answer 24

only exons

Question 25

what is transcription

Answer 25

production of MRNA using a DNA template. A gene is transcribed into an MRNA molecule

Question 26

what is translation

Answer 26

the production of polypeptides using the sequence of codons carried by MRNA
occurs in a ribosome

Question 27

describe transcription

Answer 27

DNA helicase unwinds sections of DNA ro expose the bases by breaking hydrogen bonds
RNA polymerase attaches to the exposed polynucleotide and joins complementary RNA nucleotides together forming pre MRNA
Pre MRNA is is then spliced to form MRNA which diffuses out of the nucleus

Question 28

what is splicing

Answer 28

removing introns from pre MRNA allowing different proteins to be made

Question 29

similarities of transcription and DNA synthesis

Answer 29

DNA helicase is used
phosphodiester bonds are made
use complementary base pairs

Question 30

differences of transcription and DNA synthesis

Answer 30

RNA polymerase in transcription instead of DNA polymerase
Pre MRNA is formed in transcription whilst DNA synthesis produces two DNA molecules
splicing is required in transcription but not in DNA synthesis
DNA synthesis does the whole chromosome
transcription is just one gene

Question 31

what does TRNA do

Answer 31

it had an amino acid attachment site and an anticodon loop consisting of 3 unpaired bases making TRNA specific to each amino acid

Question 32

why do amino acids need ATP in TRNA

Answer 32

so that it is activated to be picked up by TRNA

Question 33

describe translation

Answer 33

MRNA associates with ribosomes in the cytoplasm
the first two codons are on the ribosome and attract their complementary TRNA
anticodons of the TRNA join via complementary base pairing forming hydrogen bonds
with MRNA codons
peptide bonds are formed
ribosome moves onto the next codon
the first TRNA leaves the ribosome and a new one enters
another peptide bond is formed between the second amino acid and the new one
this continues until the ribosome reaches a stop codon

Question 34

what does transferase do

Answer 34

creates peptide bonds between amino acids and breaks bonds from TRNA

Question 35

what does a stop codon do

Answer 35

codes for a release factor not an amino acid