lecture 16 - how are we different?

Question 1

What are Mendel’s 3 Laws of Inheritance?

Answer 1

Segregation, Independent Assortment, Dominance

Question 2

What is the Law of Segregation?

Answer 2

When gametes form, alleles are seperate so that each gamete carries only one allele for each gene, one from each parent

Question 3

What is the Law of Independent Assortment?

Answer 3

The segregation of alleles for one gene occurs independently to that of any other gene (though this is not true for genes on the same chromosome)

Question 4

What is meiotic recombination?

Answer 4

When parts of homologous chromosomes combine to form new chromosomes with alleles from both.

Question 5

What is genetic linkage?

Answer 5

A principle whereby the closer 2 genes are on a chromosome, the less likely they are to be recombined onto different chromosomes. You are more likely to have both genes rather than just 1

Question 6

What is the Law of Dominance?

Answer 6

Some genes are dominant while others are recessive. An organism with at least one dominant allele will express the dominant.

Question 7

Do recessive alleles encode functional proteins?

Answer 7

No - the protein has a different sequence, which often results in loss of fucntion

Question 8

How is phenylalanine breakdown influenced by genes?

Answer 8

Mutations to certain genes means that the proteins required for steps in phenylalanine breakdown do not work, leading to accumulation of phenylalanine or other steps in the process (e.g. tyrosine)

Question 9

What is the genetic condition caused by the inability to break down phenylalanine?

Answer 9

PKU - phenylketonuria

Question 10

What are the symptoms of phenylketonuria?

Answer 10

Intellectual disability, seizures, behavioural/mental problems,

Question 11

How can environmental factors influence phenotype of individuals with PKU?

Answer 11

Eating a low phenylalanine diet can reduce symptoms

Question 12

How can genetics further influence phenotype in individuals with PKU?

Answer 12

genetic variation alters the efficiency of the phenylalanine transporter across the blood-brain barrier, meaning some people have less cumulative of Phe in the brain

Question 13

What is translation?

Answer 13

The process in which mRNA is used by a ribosome to produce polypeptide chains

Question 14

What are the 3 steps of translation?

Answer 14

initiation, elongation, termination

Question 15

What are the 3 key types of single amino acid mutations?

Answer 15

substitution, deletion, insertion

Question 16

What is a substitution mutation?

Answer 16

Change of one amino acid, resulting in a point mutation

Question 17

What is a deletion mutation?

Answer 17

Loss of one amino acid, resulting in a frameshift mutation

Question 18

What is an insertion mutation?

Answer 18

Insertion of an amino acid into the sequence, resulting in frameshift mutation

Question 19

What elements are required for PCR?

Answer 19

DNA nucleotides, DNA from cells, Primers specific to the gene being isolated, Taq DNA polymerase

Question 20

What does PCR stand for?

Answer 20

Polymerase Chain Reaction

Question 21

What are the steps in PCR?

Answer 21

Heat DNA to 95C to seperate DNA strands, Cool to 60C to anneal/pair the primers to the DNA sequence. heat to 72 to allow Taq DNA polymerase to copy the DNA. Repeat to exponentially amplify

Question 22

What temperature must DNA be heated to to seperate the strands in PCR?

Answer 22

95 degrees

Question 23

What temperature must DNA strands be heated to to anneal with primers in PCR?

Answer 23

~60 degrees

Question 24

What temperature must DNA be heated to to allow Taq polymerase to copy the DNA?

Answer 24

72 degrees

Question 25

How many base pairs make up typical PCR primers?

Answer 25

~20 nucleotides

Question 26

What technique is used to determine wild-type sequences from mutants?

Answer 26

Restriction enzymes are added that will only cut the DNA if a specific sequence (e.g. mutation) is present

Question 27

What restriction enzyme is used to identity and cut the MODY2 mutation?

Answer 27

HindIII

Question 28

When a restriction enzyme has been added to a sample, how can the wild type and cut mutant DNA be differentiated?

Answer 28

Via gel electrophoresis- differentiates molecules based on size, so normal will have one line while the mutant will have 2, representing the two pieces on either side of the cut (sometimes three if they are heterozygous)