Chapter 13 - Modern Understanding Of Inheritance

Question 1

What type of genes disrupted mendels model?

Answer 1

Linked genes (genes in the same chromosome) especially if they are close together

Question 2

How does recombination frequency work?

Answer 2

Genes that linked perfectly (very close together on the chromosome) have a recombination frequency of 0, while those that are perfectly unlinked (far apart in the chromosome or on different chromosomes) had a recombination frequency of 100

Question 3

What disorders occur when chromosomes behave abnormally? What are the two types called?

Answer 3

Congenital disorders

1- structural rearrangements
2- abnormalities in chromosome number

Question 4

What is a karyotype and karyogram?

Answer 4

A procedure to see the arrangements and characteristics of all 23 of your chromosomes which is shown in the karyogram

Question 5

What is the size arrangement of autosomes?

Answer 5

1-22 is largest to smallest, except 21 is shorter than 22

Question 6

What are the long and short arms called in a chromosome?

Answer 6

Long arms are q and short arms are p

Question 7

How does nondisjunction occur?

Answer 7

It occurs during meiosis when homologous chromosomes or sister chromatids fail to separate due to misalignment or incomplete synapsis or spindle apparatus dysfunction

Question 8

Individuals with the proper number of chromosomes for that species are called…; while those with an error in chromosome number are called what?

Answer 8

Correct is euploid, incorrect is aneuploid

Question 9

What is monosomy?

Answer 9

Losing one chromosome, happens if the zygote is missing an autosome or development fails

Question 10

What is trisomy?

Answer 10

Gaining an extra chromosome, these zygotes may develop offsprings that can live a long time. But excess gene dosage results in many functional and developmental difficulties due to excess gene products

Question 11

What is the most common trisomy?

Answer 11

Trisomy 21

Question 12

What is polyploidy? Where is it seen?

Answer 12

Individuals with more than the correct number of chromosome sets

Common in plants, but rare in animals

Question 13

What does triploid zygotes result from?

Answer 13

An abnormal diploid sperm fertilizing a normal haploid egg

Question 14

Sex chromosome nondisjunction in humans is relatively mild due to what?

Answer 14

X inactivation in female embryos where one X chromosome condenses into a quiescent structure called a Barr body, females can compensate for this loss of an X chromosome via dosage compensation, that is the remaining X chromosome is hyperactive and the Barr body can express a few genes usually involved in ovary and brain development

Question 15

What do individuals carrying abnormal numbers of X chromosomes do?

Answer 15

Inactivate all but one X chromosome in each cell

Question 16

XXX individuals are phenotypically what sex? What happens to them

Answer 16

Female, but experience developmental delays and reduced fertility

Question 17

XXY individuals are usually what sex? And what effects does it have?

Answer 17

Male, but have small testes, enlarged breasts, and reduced body hair

Question 18

What is the presentation in chromosomes of Klinefelter syndrome?

Answer 18

Individuals would have Y chromosome and up to 5 X chromosomes, the extra X chromosomes become Barr bodies

Question 19

What happens with individuals with only an X chromosome? What is it called?

Answer 19

They have a female genotype with short stature, webbed skin in neck, hearing and cardiac impairments, and sterility. It is called turners syndrome

Question 20

What is the cause of cri-du-chat syndrome?

Answer 20

Deletion of most or all of 5p (the small arm)