Lesson 10- Cell Division and Genetics (43-76)

Question 1

True Breeding

Answer 1

Breeding between two parents that are homozygous for genes meaning they create the 3:1 offspring

Question 2

Phenotype

Answer 2

The trait shown in the offspring, its physical appearance of trait

Question 3

Genotype

Answer 3

Genetic makeup (alleles) that determine the physical appearance

The alles the offspring demonstrates
(PP,Pp,pp)

Most traits are determined by allele pairs

Ex: widows peak (dominant) Brown eyes (dominant) over blue

Question 4

Homozygous vs Hetrozygous

Answer 4

The type of alles shown

Homozygous = PP,pp (dominant or recessive). Same genes

Heterozygous = Pp (mixed). Different genes. Dominant trait is displayed

Question 5

Punnett square

Answer 5

Determines the probability of inheriting a trait

Compares alleles from both parents

Question 6

Dominant traits

Answer 6

TT x TT = 100% with trait

TTxTt
-100% with trait
- 50% heterozygous

TTxtt
-100% with trait
-100% heterozygous

tt x tt = Trait not shown

Question 7

Heterozygous parents

Answer 7

Tt x Tt and if dominant
75% with trait
- Homozygous dominant and
heterozygous
-25% no trait
-50% heterozygous

Question 8

Recessive disorders

Answer 8

Most disorders are recessive

Recessive disorders
-Show up only in individuals homozygous for the allele

Carriers
- heterozygous individuals
* carry the recessive allele but are phenotypically normal

Ex: Cystic Fibrosis

Sickle cell anemia

Question 9

Dominant Genetic disorders

Answer 9

Disorder expressed if dominant gene is present, seen in heterozygous indiviudals

75% instead of 25%

Example: Huntington disease
-effects seen after 40 and neurogenertive

Question 10

Pedigree Analysis

Answer 10

A Pedigree:

-Family tree that describes the interrelationships of parents and children across generations
-Inheritance patterns of traits can be traced

Can trace back dominant or recessive traits

Question 11

Codominance

Answer 11

Two dominant alleles each distinctly affect the phenotype
- More than 2 allele forms

E.g. Human blood
groups

Both A and B phenotypes are dominant

Dominance vs prevalence

Domiants vs most common trait seen

Question 12

Incomplete dominance

Answer 12

Phenotype of F1 offspring is between the phenotypes of the two parental varieties.

Ex flowers: red and white to pink

Human example:
Eye/hair/skin colour?
Sickle-cell anemia
* Heterozygous people can
show mild symptoms

Question 13

Pleiotropy

Answer 13

Where one gene has multiple phenotypic effects

1 amino acid that’s gone wrong

Question 14

Polygeny

Answer 14

When traits are determined by two or more genes

Many human characters
-Vary along a continuum
-called quantitative characters

skin colour is an example: melanin has two types, dark and yellow

Question 15

Sex linked traits

Answer 15

if a mother is heterozygous for a recessive trait
-50% of daughters will be carriers
-50% of sons will have the recessive trait

Punnet square

Ex: colourblindness
Hemophilia
Baldness

Question 16

Sex linked genes

Answer 16

The chromosomes carries genes unrelated to the sex
-Males x and y
-females two x

Male have two possibilities: y and a dominant or reccesive x

Female have three: homozygous dominant x, heterozygous x and homozygous recessive x

Question 17

Sex linked disorder

Answer 17

Most are recessive and affect males
-A male who has a single X linked allele from his mothe, will have the disorder if he has the allele

• A female who has two x alleles needs recessive allele from both parents for diseases (rare)

Question 18

Gene expression

Answer 18

Having a gene does not mean its expressed

Epigenetic effects
- Histones or methylation
- Can turn on or off gene expression
- external factors determine epigenetic

Question 19

Human diseases

Answer 19

Have both genetic and environment components

Ex; heart diseases and cancer

Lifestyle choices matter, stuff like smoking may increase risk

Question 20

Character and trait

Answer 20

Character: a heritable feature, such as eye colour or hair colour

Trait: a variant of a character, such as blue eyes or brown eyes

Question 21

Generations

Answer 21

P generation – the true-breeding parents

F1 generation - hybrid offspring of the P generation

F2 generation –when F1 individuals self-pollinate

Question 22

Alleles and Locus

Answer 22

Alleles – inherited character on the genes (get one from each parent)

Locus – location on the gene