Inheritence and Mandelian Genetics - Genetics 1 & 2

Question 1

Genetic Diversity

Answer 1

Variation in genetic traits within a population.

Question 2

Why is genetic diversity essential for evolution?

Answer 2

In order for traits to be selected for, genetic diversity is needed (different combinations of alleles).

Question 3

Mutation

Answer 3

Change in bases of DNA sequence affecting genetic information - including functional and non-functional genes.

Question 4

Karyotypic Changes

Answer 4

Alterations in chromosome structure or number.

Question 5

Evolution

Answer 5

Process by which species adapt over time.

Question 6

DNA Replication

Answer 6

Process of copying DNA before cell division.

Question 7

Polymerases

Answer 7

Enzymes that synthesize DNA strands.

Question 8

How is erorr rate reduced in the DNA sequence during replication

Answer 8

Proofreading and mismatch repair

Question 9

Proofreading

Answer 9

Error-checking mechanism during DNA synthesis in proofreading domains of polymerases

Question 10

Mismatch Repair

Answer 10

Correction of base-pairing errors in DNA.

Question 11

Base-Excision Repair

Answer 11

Repair mechanism for oxidative DNA damage.

Question 12

How else can mutations occur apart from random changes to neucleotides?

Answer 12

DNA Damage. Agents causing mutatations (mutagens) cause their accumulation

Question 13

Why do we use harmful chemicals

Answer 13

They havn’t been discovered yet as a mutagen/carcinogen

Question 14

Deleterious

Answer 14

Negative, causing harm

Question 15

Why do organisms have fine-tined mutation rates

Answer 15

• Too many mutations would be deleterious
• Mutations generate genetic diversity on which evolution acts
  Successful organisms have evolved to repair their DNA efficiently, leaving just enough genetic variability for evolution to continue.

Question 16

Transition Mutation

E.g. C - T

Answer 16

Substitution of one purine for another purine.

Question 17

Transversion Mutation

E.g T - G

Answer 17

Substitution of a purine for a pyrimidine.

Question 18

3 types of substitution mutations

Answer 18

• Silent
• Nonsense
• Missence

Question 19

Missense Mutation

Answer 19

Single base change alters amino acid in protein.

Question 20

Silent mutation

Answer 20

No effect because of the degenerate nature of amino acids

Question 21

Why are missence mutations sometimes managable

Answer 21

R groups of the different amino acid being coded for can have the same charge/polarity (properties) so the 3D structure it folds to is similar enough to carry out its function.

Question 22

Frameshift Mutation

Answer 22

Insertion or deletion alters reading frame of DNA. Every subsequent codon is changed and is are each/most amino acids coded for in the final protein. Protein is unable to bind so unexpressed

Question 23

Nonsense Mutation

Answer 23

Mutation that creates a premature stop codo, producing a truncated protein.

Question 24

Where are frameshift mutations common?

Answer 24

In tumor supressor genes

Question 25

Sequence Divergence

Answer 25

Variation in DNA sequences among species. Used as a measure of evolutionary relatedness.

Question 26

How is sequence divergence used to measure evolutionary relatedness?

Answer 26

Sequences of different organisms are compared for differences, less differences = more closely related

Question 27

Conservation of sequences between different species

Answer 27

These sequences have vital fucntions for life. For instance the genes coding for histones which bind to DNA that wraps around, giving histones their shape.

Question 28

Conserved Sequences

Answer 28

DNA sequences that remain unchanged across species.

Question 29

Genome Instability

Answer 29

Allows frequent mutations leading to genetic diversity that natural selection can act on. It is also a hallmark of cancer

Question 30

Karyotype

Answer 30

Visual representation of a person's chromosomes - can be used to identify oddities in chromosome number/structure.

Question 31

Structural variants of karyotype variation

Answer 31

IMAGE

Question 32

Cancer Karyotypes

Answer 32

Extreme of genetic diersity - chromosomal variations associated with cancer.

Question 33

Source of genetic diversity that isn't mutation

Answer 33

Chromosomal changes during viral infection and meiosis

Question 34

HIV Resistance

Answer 34

Genetic mutation providing immunity to HIV.

Question 35

Natural Selection

Answer 35

Process where organisms better adapted survive.

Question 36

SARS-Cov-2 Mutation

Answer 36

Genetic changes affecting virus infectivity.

Question 37

Mendel's pea experiments

Answer 37

Only used true breeding plants and studies 7 of the plant's phenotypes. E.g pea shape and colour, and flower colour and position.

Question 38

What do we assume when doing genetic crossing experiments?

Answer 38

Gnetic occurances have direct impact on phenotype - this only occurs when 1 gene impacts a specific phenotype

Question 39

True breeding

Answer 39

Phenotypes of offspring are the same as in the parents regardless of how many times they are crossed - nothing new.

Question 40

What did Mendel deduce?

Answer 40

* Traits are controlles by a pair of inherited "factors" * One is dominant and one is recessive * Pairs segregate randomly during gamete formation - causing different impacts on the phenotyoe

Question 41

Dominant and recessive alleles are contrary to the priginal blending model of genetic inheritence

Answer 41

Previously thought that phenotypes olccured due tp blending of parents characteristics (gene)

Question 42

Predict the outcomes of an RR x rr and Rr x rr cross

Answer 42

* RR x rr: 100% Rr * R r X rr: 50% rr, 50% Rr

Question 43

Knockout mice

Answer 43

Genetically modified lab mice with one or more genes that have been intentionally inactivated

Question 44

You breed 2 heterozygous knockout mice and need homozygous knockout offspring (25%). You notice the litter is smaller than normal and when you run a gel electrophoresis you notice none of the pups are homozygous for the knockout gene. Why?

Answer 44

Pups with homozygous knockout are not viable for life so don't go to full term, hence the smaller litter. Essential genes encoding proteins vital to cellular life were knocked out.

Question 45

Embryonic lethality

Answer 45

The death of all organisms in a population during the embryonic period. It is a common phenotype in mice that have genetically engineered mutations.

Question 46

What did Mendel seek to investigate with his usage of dihybrid crosses?

Answer 46

Are characteristics of the peas (heritable traits) inherited independently (in an identifiable way from each other) or are they linked.

Question 47

Dihybrid crosses

Answer 47

Used to investigate the inheritence of two different traits and how they are combined in the offspring.

Question 48

Mendel's law of inheritence

Answer 48

1. Law of dominance 2. Law of segregation 3. Law of independent segregation

Question 49

Law of segregation

Answer 49

When a gamete is formed, the two alleles at a specific location separate, and each gamete has an equal chance of containing either allele.

Question 50

Law of independent segregation

Answer 50

During reproduction, two genes independently segregate, each independently determining one aspect of the phenotype

Question 51

Law of dominance

Answer 51

When a pair of contrasting characters are present together, only one expresses itself, while the other remains suppressed. (dominance vs recessiveness).

Question 52

Pleiotropy

Answer 52

Single gene mutation can cause a range of phenotypes ## Footnote So, the pheotypes don't appear the same in 2 patients

Question 53

Gnetic heterogeneity

Answer 53

Same penotype can be cause by a range of different genes. As a result, certain symptoms can be difficult to diagnose.

Question 54

Polygenic

Answer 54

Traits controlled by more than one gene

Question 55

Examples of polygenic traits

Answer 55

Human height, eye, hair and skin colour. These all have lots of variation within a popualtion.

Question 56

Codominance

Answer 56

Two alleles are expressed equally in an organism, resulting in the appearance of both traits/phenotypes.

Question 57

Incomplete dominance

Answer 57

Two alleles are blended/mixed rather than both expressed. It's also known as partial dominance, semi-dominance, or intermediate inheritance. ## Footnote A white and red flower would prodice a pink flower.