1.4 Protein, mutations & genetic disorders

Question 1

How many proteins are there within the human body and what do they do?

Answer 1

there are thousands of proteins which do a wide range of important tasks

Question 2

What chemical elements do all proteins contain?

Answer 2

carbon
hydrogen
oxygen
nitrogen

Question 3

What other chemical element do some proteins contain?

Answer 3

sulphur

Question 4

What are proteins held in?

Answer 4

a 3D shape by peptide bonds, hydrogen bonds and interactions between individual amino acids. (e.g. sulphur bridges)

Question 5

What do polypeptide chains do to form the 3D shape of protein?

Answer 5

fold

Question 6

What are the 2 types of protein structure and describe them?

Answer 6

fibrous proteins - flat sheets

globular proteins - wound into ball

Question 7

What will having polypeptide chains arranged in different ways give rise to?

Answer 7

the large variety of structures and shapes of proteins and ultimately contribute to their different roles (e.g. structural and enzymes)

Question 8

Give 2 examples of structural proteins?

Answer 8

keratin (hair)

collegen (skin)

Question 9

Give 2 examples of enzymes (include substrate and products)?

Answer 9

hydrogen peroxide (catalase)-----> oxygen + water
starch (amylase)-----> maltose

Question 10

What is a mutation?

Answer 10

a change in the structure or composition of an organism’s genome.

Question 11

What is an organism’s genome?

Answer 11

all the genes it contains

Question 12

What can a mutation either result in?

Answer 12

no protein or a faulty protein being expressed.

Question 13

When do mutations occur?

Answer 13

randomly and rarely

Question 14

What do mutagenic agents do?

Answer 14

Increase the rate of mutations

Question 15

Give some examples of mutagenic agents?

Answer 15

UV radiation
X-rays
Mustard gas

Question 16

What is a genetic disease?

Answer 16

a disorder which can be directly related to a person’s genotype.

Question 17

What can a mutation cause a change in?

Answer 17

the sequence of amino acids in a gene, which result in the protein it codes for not functioning as it should.

Question 18

What do most genetic disorders drastically affect?

Answer 18

a person’s phenotype

Question 19

What do single gene mutations involve?

Answer 19

the alteration of a DNA nucleotide sequence as a result

of the substitution, insertion or deletion of nucleotides.

Question 20

What is a single gene mutation that replaces an amino acid called?

Answer 20

a point mutation

Question 21

What are the 3 types of point mutations?

Answer 21

missense mutations
nonsense mutations
splice-site mutations

Question 22

Why do missense mutations occur?

Answer 22

as a result of a substitution mutation (when one nucleotide is substituted with another). This replaces one amino acid codon with another, meaning that a different amino acid with be placed in the protein chain.

Question 23

Why missense mutation called that?

Answer 23

Because they make sense, the altered codons still code for amino acids, but they don’t make the right sense, a different amino acid will be placed.

Question 24

Give an example of a missense mutation?

Answer 24

sickle-cell disease

Question 25

What nonsense mutations caused by?

Answer 25

a substitution mutation , this mutation occurs when one nucleotide is substituted with another and the resultant codon is now a stop codon.

Question 26

Why are nonsense mutations called that?

Answer 26

Since the protein chain is stopped before all of the amino acids are in position, nearly all nonsense mutations lead to non-functional proteins.

Question 27

Give an example of a nonsense mutation?

Answer 27

Ducheme muscular dystrophy (DMD)

Question 28

What do splice-site mutations alter?

Answer 28

codons that trigger the removal of introns from the primary transcript in translation. A s a consequence, these introns will not be cut out, and will remain in the mRNA sequence, coding for amino acids that would not normally appear in the polypeptide chain. This results in an altered protein that doesn’t function properly.

Question 29

What are frame-shift mutations ad give the 3 types?

Answer 29

These mutations occur when nucleotides are added or removed from the nucleotide sequence.
Deletion
Insertion
Nucleotide sequence repeat expansion

Question 30

Describe deletion mutation?

Answer 30

A nucleotide is removed from the sequence. This alters all of the triplets and therefore the amino acids from this point on.

Question 31

Give an example of a deletion mutation?

Answer 31

cystic fibrosis

Question 32

Describe insertion mutation?

Answer 32

An extra nucleotide is added to the sequence. This alters all of the triplets and therefore the amino acids from this point on.

Question 33

Give an example of an insertion mutation?

Answer 33

Tay-Sachs syndrome

Question 34

Describe nucleotide repeat expansion?

Answer 34

Some insertion or deletion mutations cause repetition of a triplet of bases. These can result in the production of a defective protein or no protein at all.

Question 35

Give an example of nucleotide repeat expansion?

Answer 35

Huntington’s disease

Question 36

What can mutations also directly affect?

Answer 36

The structure of a chromosome

Question 37

What can changes in chromosome structure sometimes be?

Answer 37

Substantial resulting in the mutation being lethal

Question 38

What are the 3 different categories of chromosome structure mutations?

Answer 38

Deletion
Duplication
Translocation

Question 39

Describe deletion as part of a chromosome structure mutation?

Answer 39

A segment of a chromosome is lost resulting in the loss of several genes.

Question 40

Describe duplication as part of chromosome structure mutation?

Answer 40

Genes from segment of a chromosome are repeated

Question 41

Describe translocation as part of chromosome structure mutation?

Answer 41

Segments of genes are swapped between different (non-homologous) chromosomes