Lecture 16 - How are we all different?

Question 1

Mendel’s laws of inheritance

Answer 1

Segregation
Independent assortment
Dominance

Question 2

Law of segregation

Answer 2

when gametes form alleles separate so each gamete carries only one allele for each gene

Question 3

Allele

Answer 3

alternative form of a gene located at same place on chromosome

Question 4

Law of independent assortment

Answer 4

The segregation of alleles for one gene occurs independently of another gene.

shuffles DNA (recombination) to get random assortment

Question 5

What is an exception to law of independent assortment?

Answer 5

Genetic linkage

2 genes close together on chromosome.

inherited together

Question 6

Law of dominance

Answer 6

Some alleles are dominant others are recessive;

an organism with at least one dominant allele will display the effect of the dominant allele.

Question 7

recessive allele

Answer 7

version of gene that does not encode a functional protein

Question 8

functional CHS enzyme produced
Mutation so no CHS mRNA (No CHS Protein)

Alleles

Answer 8

B allele - functional

b allele - mutation. no function.

Question 9

Why are we all different

Answer 9

inherit unique combination of alleles from parents.

DNA of any two people is 99.4% identical.

differs at 20 million places (0.6% of total of 3.2 billion base pairs).

5% of these differences (1 million differences) might affect how our genes function.

Question 10

If theres mutations in instructions for particular step in pathway from both parents

Answer 10

Not be able to catalyze a step

Eg alkaptonuria

Question 11

Alkaptonuria

Answer 11

Black urine disease
Not toxic

Defect in phenylalanine breakdown

Step for ring structure of phenylalanine is cleaved
Won’t break down further

Inherit disorder
Defect from both parents

one of the last steps in Phenylalanine breakdown

Question 12

Phenylketonuria (PKU) cause by

Answer 12

defect in enzyme - Phenylalanine Hydroxylase

Question 13

PKU

Answer 13

1/10000

build up of phenylalanine

decrease tyrosine

Question 14

PKU leads to

Answer 14

intellectual disability, seizures, behavioural problems, mental disorders

Question 15

Why does defect in earlier step of phenylalanine breakdown cause PKU effects?

Answer 15

Complex network Metabolic pathway

Increase Phenylalanine, Phenylpyruvate, Phenylethylamine

Decrease Tyrosine, Neurotransmitters (Dopamine, Adrenaline)

Toxic

Question 16

Genes influenced by

Answer 16

Environment (things going on outside cell, lifestyle, exercise)

Question 17

PKU special diet

Answer 17

Low protein diet

Have artificial protein substitutes
High in tyrosine
Low in phenylalanine

No symptoms live normal life

Question 18

Environment affects genetics

Answer 18

Modify behaviour

To reduce symptoms and disorder

Question 19

Environment determines how

Answer 19

some of these genetic differences affect us.

Question 20

Phenotype can be affected by your

Answer 20

GENETICS

Question 21

Phenylalanine is

transported across

Answer 21

blood-brain barrier.

Question 22

Phe Transporter

Genetic variation means

Answer 22

efficiency of this transporter differs between individuals.

Question 23

Individuals with less efficient Phe transporters have

Answer 23

lower levels of Phe in the brain and less damage (higher IQ).