Mod 5: Inheritance patterns in a Population (CQ5)

Question 1

What is population genetics?

Answer 1

The study on the genetic differences within and between populations

Question 2

How do we monitor inbreeding?

Answer 2

Comparing genomes of a random population sample to:
1. Determine how closely related population members are
2. Measure allele frequencies for unhealthy mutations

Question 3

What are the impacts of inbreeding on a population?

Answer 3

Closely related individuals can have similar ancestors -> May inherit bad alleles

Question 4

What is speciation?

Answer 4

Formation of new species

Question 5

What are cryptic species?

Answer 5

Groups of species originally thought to be the same but are different

Question 6

What happens to a population during speciation?

Answer 6

• Population stops inbreeding
• Prevents DNA from being shared between population
• Creates a barrier to gene flow

Question 7

What influences disease inheritance?

Answer 7

Many genetic disorders are affected by more than 1 gene

Question 8

What are the benefits of identifying regions of DNA with genetic disorder?

Answer 8

1. Who’s likely to be affected
2. What goes wrong in cell
3. How we can treat the disease

Question 9

What is polygenic inheritance?

Answer 9

Inheritance of an observable trait is determined by many genes -> Genes showing polygenic inheritance often have environmental factors

Question 10

What is Genome-wide association studies (GWAS)?

Answer 10

• Involves taking a DNA of an individual and looking at certain variations
• Comparing SNPs of people with a disease to those without -> Can see which SNPs are associated with a disorder

Question 11

What are the limitations of Genome-wide association studies?

Answer 11

• Population stratifications (When disorders are more common in people with a particular ancestry or ethnicity)
• Shared ethnicity -> More likely to share SNPS
• HOWEVER, shared SNPS may not be associated with diseases

Question 12

How can we identify Primate Evolutionary Relationships?

Answer 12

Base ideas about evolutionary relationships of different species on their observable characteristics + DNA evidence

Question 13

How can we study Human Migration?

Answer 13

By using population genetics to identify how long ago different groups of humans migrated:
-How genetic markers vary across people in different population
- Differences between genetics increase with distance
- Rate of DNA mutation -> work out rate that new genetic markers arise, and how long populations last shared a common ancestor

Question 14

In which sections of DNA are SNPs found?

Answer 14

• Introns -> Non-effective
• Exons -> Effective
• Intergenic regions -> Non-effective

Question 15

What is Polymerase Chain Reaction (PCR)?

Answer 15

Technique used to amplify DNA, in vitro -> Making lots of copies of a specific region of DNA

Question 16

Define in vitro

Answer 16

In a test tube rather than an organism

Question 17

What are the materials involved in PCR?

Answer 17

1. DNA sample
2. Free nucleotides
3. HEAT STABLE DNA polymerase (speed up DNA synthesis)
4. Primers (short single stranded pieces of chemically synthesis DNA which prime target region)
5. Buffer (Liquid which ingredients are added to)

Question 18

What are the steps in PCR?

Answer 18

1. Denaturation (95C) -> DNA separates to form single strands
2. Annealing (55C) -> Primers bind to DNA strands
3. Extension (72C) -> DNA polymerase synthesis new DNA

Question 19

What is Gel Electrophoresis?

Answer 19

Separate and visualise DNA fragments according to size (usually amplified by PCR)

Question 20

What are the steps in Gel Electrophoresis?

Answer 20

1. Prepare setup
   - Pour liquid agarose gel in mould
   - Insert well comb
   - Once set, place into gel box
   Immerase gel with buffet (conduct electricity)
2. Load sample and DNA ladder
   - DNA loaders (mixture of KNOWN fragments) added in its own well
   - Record what sample is added in each well
3. Run the gel
   - Put a current through the gel ->
   The gel allows to separate DNA according to size
4. Visualising DNA fragments
   - Add dye to stain DNA fragments

Question 21

What is DNA sequencing?

Answer 21

Process of determining the sequence of nucleotide in a piece of DNA

Question 22

What are the steps in DNA sequencing?

Answer 22

1. Collect DNA sample
2. Extract DNA from sample
3. Amplify DNA
4. Perform Songer sequencing reaction (Use 4 ‘special’ PCRs)
5. Determine DNA sequence (Run PCR reaction on electrophoresis gel to determine length of fragments)

Question 23

What is DNA profiling?

Answer 23

Process of analysing DNA variations (Genetic markers) for the purpose of identification

Question 24

What is a Short Tandem Repeat (STR)?

Answer 24

String of repeating nucleotide units, no. of units varies between people
-> Non-coding DNA, differences have no impact on health

Question 25

What are the steps in DNA profiling?

Answer 25

1. Collect DNA sample 2. Extract DNA from sample 3. Amplifying STR fragments 4. Determine lengths of STRs 5. Interpreting electrophoresis gel

Question 26

What are the applications of DNA profiling?

Answer 26

1. Determining parentage 2. Identification of unknown person

Question 27

How do we use DNA profiling to determine parentage?

Answer 27

- Every person has 2 alleles (copies) of every STR in their genome - STR alleles in a person’s DNA profile should be present in their mother’s and/or father’s DNA profile - DNA profile consist of combination of parent’s alleles

Question 28

How do we use DNA profiling to identify an unknown person?

Answer 28

A sample taken from the scene is used to generate a DNA profile. Victim/suspect is the person whose DNA profile is a complete match