DNA and protein synthesis

Question 1

where is DNA found

Answer 1

they are found in the nucleus of the cell where they form chromosomes

Question 2

what is a double helix

Answer 2

two strands of nucleotides bases making up the DNA molecule twisted together in a helix shape.

Question 3

what are the building blocks of DNA and what are they made up with

Answer 3

Nucleotides
1) sugar molecules( pentose sugar)
2) phosphate molecule( as a backbone)
3) nitrogenous base

Question 4

what are the two groups of nitrogenous bases

Answer 4

purines and pyrimidines

Question 5

what are purines

Answer 5

guanine and adenine which have a double ring structure

Question 6

what are the pyrimidines

Answer 6

cytosine, thymine( DNA) and uracil( RNA), which have a single ring structure which have a single carbon-nitrogen ring structure

Question 7

what are nitrogenous bases held together by

Answer 7

weak hydrogen bases

Question 8

what is the function of DNA

Answer 8

1) carry hereditary information in the form of genes
2) it controls the growth and development of an organism coding for protein synthesis
3) It can make an identical copy of itself to pass genetic info down generations

Question 9

what is DNA replication catalysed by and when does it occur

Answer 9

it is catalysed by DNA polymerase and during the interphase of the cell cycle

Question 10

what is interphase

Answer 10

the stage in the life cycle of a cell where the cell grows and DNA is replicated

Question 11

what is a polymerase

Answer 11

enzymes that catalyze the synthesis of DNA or RNA polymers whose sequence is complementary to the original template

Question 12

stages of DNA Replication

Answer 12

1) Double helix unwinds and the base pairs bonds break and they unzip
2) Single chain of nucleotides attach to base pairs.
3) Daughter DNA will be same as parent DNA due to the sequence of base pairs

Question 13

what is DNA

Answer 13

Deoxyribonucleic acid (abbreviated DNA) is the molecule that carries genetic information for the development and functioning of an organism

Question 14

what is RNA

Answer 14

Ribonucleic acid (abbreviated RNA) is a nucleic acid present in all living cells that has structural similarities to DNA. Unlike DNA, however, RNA is most often single-stranded.

Question 15

what does RNA do

Answer 15

it carries instructions from DNA in the nucleus to ribosomes in the cytoplasm for protein synthesis

Question 16

what are the three types of RNA

Answer 16

1) mRNA ( messenger RNA)
2) tRNA ( transfer RNA)
3) rRNA ( ribosomal RNA)
and they are all produced in the nucleus

Question 17

what are the two stages of protein synthesis

Answer 17

transcription and translation

Question 18

what happens in transcription

Answer 18

mRNA is formed in the same way that DNA replication takes place.

1)small piece of DNA unwinds to form a ladder shape

2) DNA strands separate as the H bonds between the bases break. the enzyme RNA polymerase controls this.

3) the polymerase attaches and moves along the DNA strand that is also called a template. new nucleotides pair with their complimentary DNA nucleotides

4) the nucleotides joins up, a sugar phosphate backbone is added and a new strand of mRNA is formed. the sequence of the template the sequence of the nucleotides is determined by the DNA nucleotides

Question 19

what does the mRNA do once formed

Answer 19

the strand of mRNA breaks away from the DNA, the DNA then re-zips.
The small mRNA moves through the pores of the nuclear membrane and carries the genetic code to the ribosomes which are the site of protein synthesis.
The genetic code is carried as a sequence of “ codewords” which are transcribed to the mRNA. Each ‘codeword” is made up of three bases known as a codon eg cytosine adenine and guanine.

Question 20

what is the process of translation

Answer 20

the main aim of translation is the formation of a polypeptide chain or protein from the mRNA
1) mRNA binds to the ribosomes, found in the cytoplasm, which contain rRNA and protein
2) Ribosomes move down the mRNA facilitating the pairing up of mRNA codons to tRNA anti-codons
3)Transfer RNA carrying amino acids on one end and anti codons on the other end line-up with complimentary codons in mRNA
4) peptide bonds form between adjacent amino acids to form a polypeptide.

Question 21

what is a polypeptide bond

Answer 21

type of bond that forms between amino acids

Question 22

what are amino acids

Answer 22

building blocks( monomers ) of protein

Question 23

what are codons

Answer 23

series of three nucleotides bases (a triplet) that forms the code units of transcription.

Question 24

what are anti-codons

Answer 24

Codons present on the tRNA molecules, which are complimentary to the codons on the mRNA strands

Question 25

what are the differences between DNA and RNA

Answer 25

DNA is double stranded and longer than RNA.
2) the bases pairs are:
Guanine-cytosine
Adenine-thymine
While RNA is single stranded and shorter than DNA .
2) the base pairs are:
Guanine- Cytosine
Adenine- Uracil

Question 26

what is gene mutation

Answer 26

gene mutations are small, localized changes in the structure of DNA strands.
Changes that involves a single nucleotide are called point mutations, this may occur by:
1) substitution: one nucleotide is exchanged for another
2) insertions: an extra nucleotide is added to DNA molecules
3) Deletions: a nucleotide is removed from the DNA molecule

Question 27

when was it discovered that characteristics were passed down from parents to child

Answer 27

it was discovered by Austrian monk Gregor Mendel in 1863.

Question 28

what did Maurice Wilkins and Rosalind Franklin obtain

Answer 28

in 1952 hey were the first to obtain x-ray diffraction images of DNA fibres.

Question 29

what happened in 1953

Answer 29

James Watson and Francis Crick began to examine the DNA structure using previous x-ray diffraction images

Question 30

what did Erwin Chargaff do

Answer 30

he in 1950 discovered the double helix structure of DNA and started research on the base pair makeup.

Question 31

what happened in 1919

Answer 31

Phoebus Levine identified that DNA was made up of a base, sugar and phosphate nucleotide unit