Chapter 7 - Inheritance

Question 1

What are the 2 factors that mae us resemble our parents

Answer 1

Nature and nurture

Question 2

What is heredity

Answer 2

the passing of characteristics from parents to offspring

Question 3

What is selective breeding

Answer 3

choosing which strands we mate together to obtain certain characteristics in the offspring

Question 4

What is segregation

Answer 4

youve got two copied of each gene but only one copy is put into each gamete during meiosis

Question 5

Give two examples of single gene traits

Answer 5

Fur length in cats

Coat color in cats

Question 6

What is a single gene trait

Answer 6

A trait controlled by only one gene

Question 7

Give two examples of multiple gene traits

Answer 7

eye color, skin color

Question 8

Which plant did Mendel used for his experiments?

Answer 8

Pea plants

Question 9

What did Mendel was looking for in his experiments?

Answer 9

Looked for “true breeding plants”: when you breed them together, they always give the same offspring (ex all purple flowers)

Question 10

How are called Mendel’s “true breeding” plants?

Answer 10

Homozgous

Question 11

What happened when Mendel tried to cross true breeding purple plants w true breeding white plants? Why?

Answer 11

• Got only purple flowers offspring
• Why? Because the purple trait is a dominant trait, and the white one is recessive (dominant always wins over recessive)
• In the “grandchildren” of this breeding, white flowers came back

Question 12

How do we write dominant alleles? Recessive?

Answer 12

Dominant allele = always uppercase

Recessive allele = lowercase

Question 13

What is a homozygous gene?

Answer 13

One that has only 1 recessive or dominant allele twice

Question 14

What is a heterozygous gene?

Answer 14

Has 1 dominant allele and 1 recessive

Question 15

How are dominant or recessive genes transferred to offspring?

Answer 15

Each parent puts into every gamete a single set of instructions for building the trait
Offspring receives 2 copies and the expression of the trait depends on the combinations of genes that this organism has for a specific locus

Question 16

What is Mendel’s law of segregation?

Answer 16

The principle that during the formation of gametes, the two alleles for a gene separate, so that half the gametes carry one allele, and half the gametes carry the other

Question 17

What is a Punnett square?

Answer 17

A diagram tracing the outcomes of a cross between 2 individuals

Question 18

What are the steps to making and understanding a Punnett square?

Answer 18

Step 1: make sure the genotypes are ok (ex: mm, and MM)
Step 2: figure out which gametes they can produce (ex: m and m, and M and M)
Step 3: analyze possible combinations (ex: 1/4 homozygous dominant, 2/4 heterozygous Mm, etc)
Every fertilization outcome is different than the other (independent events)

Question 19

Why is it not always possible to determine a genotype by observing the phenotype?

Answer 19

Because more than one gene might be involved in the part of the phenotype observed (ex skin color)

Question 20

What can we do when we do not know the genotype of a parent? How is that called?

Answer 20

We cross (i.e., mate) an individual exhibiting a dominant trait but whose genotype is unknown with an individual that is homozygous recessive. Then we examine the phenotypes of their offspring.
This is called a test-cross
Also, we can guess which parents had which genotype depending on who has the condition or not and if it's recessive or dominant

Question 21

What is a pedigreed animal?

Answer 21

One that we know its family tree (therefore can guess its genotype more easily)

Question 22

What is incomplete dominance?

Answer 22

The case in which the heterozygote has a phenotype intermediate between those of the two homozygotes; an example is pink snapdragons, with an appearance intermediate between that of a homozygote for white flowers and a homozygote for red flowers.

Question 23

How do we write incomplete dominance in Punnett squares?

Answer 23

(in example of red and white flowers) -

C(exposant)w C(exposant) r; why? Because upper-case and lower-case are only for 100% dominant or recessive genes

Question 24

What would happen if we bred 2 CwCr pink flowers (incompletely dominant)

Answer 24

1 red (CrCr), 1 white (CwCw) and 2 pink (CwCr)

Question 25

What is codominance?

Answer 25

We see the phenotype of both alleles when both or none are dominant
EX: dad with vertical lined shirt, mom horizontal, kid has squarred shirt

Question 26

What is multiple allelism?

Answer 26

A single gene has more than 2 alleles

Ex: blood type can be A, O, B, some people are AB

Question 27

What is a polygenic trait?

Answer 27

several genes interact together to give a certain phenotype
(Basically multiple gene traits)
***Each individual still has only 2 alleles, but the whole population contains more than 2 for the same gene

Question 28

What happens to someone who is heterozygot for sickle cell anemia?

Answer 28

They wont have the disease, but they will be immune to malaria (since this deformation of the red blood cells make us immune to malaria)

Question 29

What are additive effects?

Answer 29

Effects from alleles of multiple genes that all contribute to the ultimate phenotype for a given characteristic.

Question 30

What is pleiotropy

Answer 30

A phenomenon in which an individual gene influences multiple traits. (ex sickle cell disease influences immunity to malaria)

Question 31

Why are men most likely to be colour blind then females?

Answer 31

The “R or r” trait for normal (R) or colourblind (r) vision is on the X chromosome; men have XY, therefore they have 50-50% chance of being color blind; while women (XX) can be Rr, RR, rr (1/3 chances of being color blind).

Question 32

Phenotypes are a product of genotype AND…

Answer 32

Its interaction with the environment

Question 33

What are linked genes?

Answer 33

Genes being close together on the chromosomes often come together when they are passed to offspring (very rare, most genes travel alone)