DNA and Chromosomes

Question 1

What is a triplet?

Answer 1

A sequence of 3 bases on a Dan, which codes for a specific amino acid.

Question 2

what is the genetic code?

Answer 2

The triplets available in all organisms, are known as the genetic code.

Question 3

What are the 3 features of the genetic code?

Answer 3

degenerate, non-overlapping, universal.

Question 4

what is meant by universal?

Answer 4

Because the same triplet, codes for the same amino acid, in almost all organisms.

Question 5

what is meant by degenerate?

Answer 5

Because more than one triplet, codes for the same amino acid.

Question 6

what is meant by NON-overlapping?

Answer 6

Because each nucleotide is only part of one triplet.

Question 7

What is an intron?

Answer 7

a triplet which does not code for a polypeptide chain.

Question 8

What is an exon?

Answer 8

A triplet which does code for a polypeptide chain

Question 9

define the term gene.

Answer 9

A gene is a base sequence of DNA, that codes for the amino acid sequence of a polypeptide, and a functional RNA.

Question 10

What is a locus?

Answer 10

The fixed position of a gene, on a particular DNA molecule, is known as the locus.

Question 11

what is the genome?

Answer 11

It is the complete set of genes in a cell.

Question 12

what is the proteome?

Answer 12

The full range of proteins, a cell is able to produce.

Question 13

What is a gene mutation?

Answer 13

changes in the base sequences of DNA on a chromosome.

Question 14

what are the two factors that can cause a gene mutation?

Answer 14

DNA replication, and mutagenic agents

Question 15

What are the two types of even mutations?

Answer 15

Base deletion mutation, and base substitution mutation.

Question 16

Explain base deletion mutation.

Answer 16

occurs when a nucleotide, is removed from a DNA sequence.

This causes a frameshift ( a change to the sequence of triplets).

this in turn, changes the sequence of
amino acids that are coded for.

This results in a large change to the primary structure of a protein.

Question 17

Explain base substitution mutation.

Answer 17

Occurs when a base is swapped out for a different one..
This mutation only affects a single triplet, in the DNA sequence.

Question 18

What are the two possible results of a base substitution reaction?

Answer 18

1. It can either result In a different amino acid, thus changing the primary structure of a protein.
2. It can either result in the same amino acid, which doesn’t change the primary structure.

THIS OCCURS BECAUSE THE GENETIC CODE IS DEGENERATE.

Question 19

Explain how mutations affect the structure of a protein.

Answer 19

Mutations that alter the primary structure of proteins, also alter the bond within its tertiary structure ( hydrogen, ionic, disulfide ), thus leading to a non-functional protein, bur VERY RARELY, a benefit to the protein, which increases its function.

Question 20

state the difference between DNA in prokaryotes, and DNA in Eukaryotes.