10.2 Inheritance

Question 1

How do unlinked chromosomes separate?

Answer 1

The genes found on these chromosomes segregate independently of the alleles of other genes.

Question 2

How do linked chromosomes separate?

Answer 2

They DO NOT segregate independently. ONLY RECOMBINE BY CROSSING OVER

Question 3

How do you make a dihybrid cross?

Answer 3

A dihybrid cross is the one with 16 squares. You take the genotypes of the parents.

Question 4

In questions when it gives you == (Inheritance) does it go straight or diagonal?

Answer 4

Get dragged to either side so it is STRAIGHT.

Question 5

How do you represent linked genes?

Answer 5

= sign ones!
Crossing over occurs diagonally or with the one directly below.
But with the assortment it is like you go to the poles so the top ones go off together and the bottom ones go off together.

Question 6

What did Thomas Hunt Morgan show us?

Answer 6

Linked genes are not independently assorted.

Linked genes can only be recombined by crossing over.

Question 7

What are linked genes?

Answer 7

Ones that are on the same chromosome and only separate by crossing over.

Question 8

What can result in recombinants?

Answer 8

• Unlinked genes - crossing over, independent assortment
• Linked genes - crossing over
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Question 9

What are linked genes?

Answer 9

Gene loci are said to be linked if they are on the same chromosome.

Question 10

What are homologous genes?

Answer 10

If two chromosomes have the same sequence of genes they are homologous. Homologous chromosomes are not usually identical to each other because, for at least some of the genes on them, the alleles will be different.

Question 11

What are autosomes?

Answer 11

Non sex chromosomes

Question 12

What is sex linkage?

Answer 12

When the genes are located on an X chromosome.

Question 13

What are the two types of variation?

Answer 13

Discrete or continuous

Question 14

What is discrete variation?

Answer 14

Where individuals fall into a number of distinct categories. For example blood groups.

Question 15

What is continuous variation?

Answer 15

The phenotypes of polygenic characteristics tend to show continuous variation.
There are examples of inheritance in which two or more genes affect the same character. The genes have an additive effect.
For example skin colour

Question 16

What is polygenic inheritance?

Answer 16

There are examples of inheritance in which two or more genes affect the same character. The genes have an additive effect. This produces continuous variation.

Question 17

Give an example of environmental influence to characteristics?

Answer 17

Skin colour which is a polygenetic characteristic can also be influenced by the environment.

Question 18

What is a recombinant?

Answer 18

An individual that has a new chromosome of piece of DNA with a new combination of alleles from either of the original parents.

Question 19

What is the difference between chi squared for ecology and for inheritance crosses?

Answer 19

For ecology the expected frequencies are calculated by doing rowxcolum total / overall total. Whereas in inheritance crosses they are calculated by just looking at the probability of each one and multiplying it by the total.