4A - DNA, RNA And Protein Synthesis

Question 1

Eukaryotic DNA

Answer 1

• Linear DNA - chromosomes
• long and wound up
• wound around proteins called histones
• histones help to support the DNA
• coiled up tightly to make a compact chromosome

Mitochondria and chloroplasts have own dna

Question 2

Prokaryotic DNA

Answer 2

Shorter and circular

• also carry chromosomes
• no histones
• condensed by supercoiling

Question 3

DNA contains genes

Answer 3

Gene= a sequence of DNA bases that codes for a polypeptide or functional RNA

• sequence of amino acids forms the primary structure of a protein
• different polypeptides have a different number and order of amino acids. It’s the order of the bases in a gene that determines the order of amino acids in a polypeptide

Question 4

How is an amino acid coded for

Answer 4

By a sequence of 3 bases called a triplet

Question 5

First stage of protein synthesis

Answer 5

DNA is copied into mRNA

Question 6

Functional RNA

Answer 6

Genes that don’t code for a polypeptide code for functional RNA instead. Which is rna molecules other than mRNA whcih perform special tasks during protein susnthesis

tRNA

rRNA

Question 7

Genome

Answer 7

Complete set of genes in the cell

Question 8

Proteome

Answer 8

Full range of proteins that the cell is able to produce

Question 9

Introns

Answer 9

• the section of some genes that do code for polypeptides contain sections that’s DONT code for amino acids
• can be several within a gene

Removed during protein synthesis so they don’t affect the amino acid order

Only in eukaryotes

Question 10

Exon

Answer 10

Bit of gene that does code for an amino acid

Question 11

Non coding repeats

Answer 11

Regions of multiple repeats

DNA sequences that repeat over and over

-don’t code for amino acids

CCTTCCTTCCTT

Question 12

Alleles

Answer 12

Genes can exist in more than one form

= different versions of the same polypeptide

• due to order of bases in each allele

Question 13

About homologous chromosomes

Answer 13

23 pairs of chromosomes

Pairs of Matching chromosomes

Both chromosomes are the same size and have the same GENES , although the could have different alleles

Question 14

Locus

Answer 14

Fixed position where alleles coding for the same locus on each chromosome in a homologous pair

Question 15

mRNA

Answer 15

• made during transcription
• carries genetic code from DNA to ribosomes, where it’s used to make a protein during translation
• single polynucleotide strand

Question 16

Codons in mRNA

Answer 16

3 adjacent bases

Question 17

TransferRNA

Answer 17

• involved in translation
• carries the amino acids that are used to make proteins to the ribosomes
• a single polynucleotide strand
• folded in a clover shape ; by hydrogen bonds
• anticodon at one end abs amino acid binding sure at the other end

Question 18

Anticodon in tRNA

Answer 18

Specific sequence of 3 bases at one end

Question 19

First stage of protein synthesis

Answer 19

Transcription

Question 20

Transcription

Answer 20

(mRNA copy of a gene is made from DNA)