DNA Genes and chromosomes

Question 1

DNA in prokaryotes
all types

Answer 1

single circular DNA molecule can be referred to as a nucleoid

plasmids are very small circular DNA
only containing a few genes

Question 2

histones in prokaryotes

Answer 2

DNA in prokaryotic cells have noc histones

Question 3

what are chromosomes made from

Answer 3

one long condensed DNA molecule associated with histones

Question 4

purpose of histones

Answer 4

organise and condense DNA tightly so that it fits in the nucleus

Question 5

what seals the ends of chromatids

Answer 5

protective structures called telomeres

Question 6

Dna in mitochondria and chloroplast name

Answer 6

mtDNA
cpDNA

Question 7

what is DNA in mitochondria and chloroplasts like

Answer 7

short circular
associated with no proteins
found in matrix and stroma

Question 8

gene definition

Answer 8

base sequence of DNA that codes for the amino acid sequence of a polypeptide

Question 9

function of mRNA

Answer 9

base sequences on mRNA molecules are ised by ribosomes to form polypeptide chains

Question 10

function of tRNA

Answer 10

amino acids are carried to the ribosome by transfer RNA molecules

Question 11

rRNA function

Answer 11

ribosomal RNA molecules form part of the structure of ribosomes

Question 12

what determines the shape and behaviour of the protein

Answer 12

the shape and sequence of amino acids (primary structure)

this means that genes in DNA controls protein structure

Question 13

do chromosomes contain lots of genes each

Answer 13

yes

Question 14

position of a gene

Answer 14

locus

Question 15

name for the different forms of genes that can exist

Answer 15

alleles

Question 16

difference between alleles and original gene

Answer 16

slightly different nucleotide sequences but still occupy same locus on the chromosome

Question 17

what is the DNA nucleotide base code

Answer 17

three letter code (codon) which codes for one amino acid per codon

Question 18

how to know where individual genes start and stop

Answer 18

some codons code for start and end

Question 19

importance of the start and stop codon

Answer 19

ensures that the cell reads the DNA correctly and produces the correct sequences of amino acids

Question 20

what are degenerate codons

Answer 20

there are 4 bases so 64 different triplets available however only 20 occur in proteins

this means that many codons code for the same amino acid which means this code is degenerate

Question 21

what is meant by a universal code

Answer 21

almost every organism uses the same triplet code = same amino acid

Question 22

what is non coding DNA

Answer 22

DNA that doesnt code for any amino acids

Question 23

where does non coding DNA occur

Answer 23

between genes as many base sequences will be repeated

can also be found in introns in genes

Question 24

what happens to introns just before the m,RNA leaves the nucleus

Answer 24

non coding introns are removed and the coding sections are joined together in splicing

Question 25

where is most non coding DNA in eukaryotic dna

Answer 25

introns which repeat throughout gene

Question 26

state where telomeres are found within a chromosome as well as their function

Answer 26

end of chromosome
protect DNA from damage

Question 27

Dna replication proccess

Answer 27

DNa is unzipped by DNA helicase - breaking hydrogen bonds

DNA polymerase adds free floating nucleotides to each unzipped strand

DNA polymerase can only work in the 3 to 5 prime direction

Question 28

which way can DNA polymerase only work

Answer 28

DNA polymerase can only work in the 3 to 5 prime direction