GENETIC CONTROL AND PROTEIN SYNTHESIS

Question 1

DNA and RNA are:

Answer 1

macromolecules that are polymers of nucleotides = polynucleotides

Question 2

what is the structure of a nucleotide?

Answer 2

pentose sugar:
deoxyribose in DNA
ribose in RNA

phosphate group

nitrogen base

Question 3

what are the 5 types of nitrogen bases

Answer 3

purine bases:
Adenine
Guanine

pyrimidine bases:
Thymine
Cytosine
Uracil

Question 4

DNA contains which bases?

Answer 4

ATGC

Question 5

RNA contains which bases?

Answer 5

AUGC

Question 6

what is the structure of a DNA molecule?

Answer 6

DNA is a double stranded molecule of two helical polynucleotide chains containing deoxyribose sugars

Question 7

what are the properties of a polynucleotide?

Answer 7

the chain is formed of a sugar phosphate backbone that nucleotides are linked to by phosphodiester bonds

Question 8

what links two nitrogen bases together:

Answer 8

purine bases: adenine and guanine = two hydrogen bonds

pyrimidine bases: thymine, cytosine and uracil = three hydrogen bonds

Question 9

what are the purine bases?

Answer 9

purine bases: two hydrogen bonds and 2 rings
Adenine
Guanine

Question 10

what are the pyrimidine bases?

Answer 10

pyrimidine bases: three hydrogen bonds and 1 ring
Thymine
Cytosine
Uracil

Question 11

the two strands are:

Answer 11

complementary to each other

Question 12

what is the structure of chromosomes?

Answer 12

DNA is coiled and wrapped around Histone proteins forming chromatin

Question 13

what is the role of Histone proteins?

Answer 13

protects DNA and prevents it from tangling in the nucleus

Question 14

how does DNA replicate?

Answer 14

helicase enzyme unwinds and separates the two DNA strands

DNA polymerase forms a new strand by adding complementary bases from the old strand forming a new strand called the leading strand in a 5’ to 3’ direction

DNA polymerase forms another strand by adding complementary bases from the old strand in small sections called Okazaki fragments forming a new strand called the lagging strand in a 3’ to 5’ direction

Okazaki fragments are joined together by DNA ligase

Question 15

why is replication semiconserative?

Answer 15

because each new DNA molecule consists of one new strand and one old strand

Question 16

describe the experimental evidence supporting semiconservative replication

Answer 16

bacteria was put in 15N medium so that the DNA only contained 15N

a sample of the bacteria were put in a 14N medium and were allowed to grow and a sample was taken every hour

the samples DNA were extracted and put in a cesium chloride solution

it was found that the heavier the DNA, the closer it was to the bottom of the tube

Question 17

what are telomeres?

Answer 17

regions of of repeated nucleotide sequences at the end of each chromatid

Question 18

what are the roles of telomeres?

Answer 18

to protect the important genetic information from being lost during cell division

Question 19

how many amino acids are in 1 base?

Answer 19

4 amino acids

Question 20

what are the properties of RNA?

Answer 20

single stranded
has ribose sugar instead of deoxyribose
has uracil instead thymine
is shorter than DNA

Question 21

what is mRNA?

Answer 21

it is made in the nucleus by the process of transcription

during transcription, the mRNA uses DNA as a template for complementary base pairing.

the DNA’s base triplets are converted into mRNA codons

Question 22

the triple code TAC codes in to what codon?

Answer 22

AUG

Question 23

1 codons code for how many amino acids?

Answer 23

1

Question 24

what is tRNA?

Answer 24

each tRNA molecule has a sequence of 3 bases that are called anticodons and are complementary to codons on mRNA molecules.
each anticodon determines the type of amino acid

Question 25

what is the anticodon for the codon AUG?

Answer 25

UAC

Question 26

what is transcription?

Answer 26

the process in which DNA acts as a template to code for a strand of mRNA with complementary bases

Question 27

what happens in transcription?

Answer 27

the enzyme helicase unwinds and separates the two DNA strands

RNA polymerase forms a sugar phosphate backbone holding the mRNA nucleotides

the mRNA, with its series of codons, leaves the nucleus through nuclear pores to the cytoplasm

the DNA rewinds into a double helix again

Question 28

what happens in translation?

Answer 28

mRNA combines with a ribosome in the cytoplasm

tRNA molecules attach to the ribosome and their anticodons pair with the appropriate codons on the mRNA strand

tRNA have amino acids attached to them that bond to another amino acid on another tRNA molecule forming a peptide bond

the ribosome moves along the mRNA until it is exposed to a stop codon

Question 29

what happens in translation?

Answer 29

mRNA combines with a ribosome in the cytoplasm

tRNA molecules attach to the ribosome and their anticodons pair with the appropriate codons on the mRNA strand

tRNA have amino acids attached to them that bond to another amino acid on another tRNA molecule forming a peptide bond

the ribosome moves along the mRNA until it is exposed to a stop codon

Question 30

what is sickle cell anemia?

Answer 30

an inherited disease which results from a mutation in the gene coding for haemoglobin

Question 31

what amino acid is different in a sickled cell anemia?

Answer 31

valine instead of glutamate

Question 32

what type of mutation is sickle cell anemia?

Answer 32

single base substitution