proteinsynthesis

Question 1

define gene

Answer 1

base sequence of DNA that codes for the aminoacid sequence of a polypeptide or a functional RNA

Question 2

define gene locus

Answer 2

the fixed position a gene occupies

Question 3

define chromsome

Answer 3

one DNA molecule folded into a condensed form, wrapped around histone proteins in eukaryotes

Question 4

what is an intron

Answer 4

DNA base sequences within genes which dont code for an amino acid sequence

Question 5

what is an exon

Answer 5

DNA base sequences within genes that code for an amino acid sequence

Question 6

what are non-coding multiple repeates

Answer 6

DNA base sequences betwen genes which do not code for an amino acid sequence

Question 7

why is genetic code known as degenerate

Answer 7

more than one triplet can code for the same amino acid

Question 8

why is genetic code known as non-overlapping

Answer 8

every triplet codes for one amino acid

Question 9

why is genetic code described as universal

Answer 9

the same tiplets code for the same amino acids in all living organisms

Question 10

what is the genome

Answer 10

the complete set of gene in a cell

Question 11

what is the proteome

Answer 11

full range of proteins that a cell is able to produce

Question 12

state the differences between a DNA nucleotide and an RNA nucleotide

Answer 12

• DNA nucleotides consist or a phosphate group, a deoxyribose sugar and a base whereas RNA nucleotides consist of a phosphate group, a ribose. sugar and a base
• instead of thymine on DNA, RNA has uracil
  -DNA is a double helix, whereas RNA is only one polynucleotide strand

Question 13

describe the structureof mRRNA

Answer 13

• single stranded polypeptide chain

Question 14

describe th structure of tRNA

Answer 14

one polynucleotide chain with regions where it is double stranded giving it a clover leaf structure.
- has a binding site complimentary to a specific amino acid
- has a regio of 3 bases known as an anticodon.

Question 15

what is a triplet

Answer 15

3 DNA bases whihc ocde for a specific amino acid

Question 16

what is a codon

Answer 16

a sequence of three bases on mRNA molecule which code for a specific amino acid

Question 17

what is an anticodon

Answer 17

a sequence of 3 bases on a tRNA molecule which code for a specific amino acid

Question 18

what is splicing

Answer 18

process by which introns are removd from the mRNA strand.

Question 19

describe the process of transcription

Answer 19

• an ezyme attaches to and unwinds DNA double heliix at site to be transcribed
• hydrogen bonds between the two strands are broken, DNA strands separate
• one strand is used as a template
• free RNA nucleotides join to the exposed DNA bases and bind via complimentary base pairing: adenine to thymine, cystosin to guanine.
• the ezyme RNA polymerase joiins free RNA nucleotides toogether forming phosphodiester bonds which form pre-mRNA ehich contain intrns and exons.
• introns are removed by splicing
• exons are joined together tp produce an RNA molecules that coes for the protein or functional RNA

Question 20

describe the process of translation

Answer 20

-mRNA attatches to ribosome
- 2 codons fit into the ribsome at one time
- tRNA carrying a specific amino acid binds to the first codon on mRNA via complimentary base pairing
- a second tRNA strand carrying a specific amino acid binds to second codon on mRNA starnd via complimentary base pairing with its anticodon.
- enzymes join aminoacids together forming pepptide bonds using energy from hydrolysis of ATP
- ribosome moves onto netx codon
- tRN is removed fom first codon and collects another of the same amino acid.
- anoher tRNA carrying a specific amino acid binds to the 3rd codon on mRNA via complimentary base ppairing with its anticodon and a new peptie bond is formed
- this process repeats until a stop codon is reaached
- polyypeptide detaches from the ribosome.

Question 21

describe the differences in DNA between prokaryotic/ chloroplast/ mitochondria DNA and Eukaryotic DNA

Answer 21

prokaryotic, chloroplast and mitochondria DNA:
- circular
- shorter than eukaryotic
- not associated with histone proteins
- does not form chromosomes
-does not contain no-coding DNA

eukaryotic DNA:
- linear DNA
- associated with histone proteins
- forms chromosomes
- contains introns and no-coding multiple repeats