Ch 3- Genetics

Question 1

How many genes does the human genome contain? On how many pairs of chromosomes?

Answer 1

30 000-80 000 genes on 23 pairs of chromosomes

Question 2

Basic genetic material formed by pairs of nucleotides

Answer 2

DNA

Question 3

For each pair of chromosomes, genes for the same trait in the same location (eye colour or nose shape)

Answer 3

Alleles

Question 4

A process with body cells by which 2 identical cells are produced

Answer 4

• Mitosis

Question 5

What is meiosis?

Answer 5

• A process by which 4 cells are produced, with each containing only 23 chromosomes called gamates (sperm or ova that will combine at conception to form a new individual)

Question 6

Crossing over occurs during _____

Answer 6

• Meiosis

Question 7

True or false: crossing over virtually assured that no 2 ppl (except identical twins) will ever have exactly the same genes

Answer 7

• True

Question 8

________ established that certain traits are transmitted from parent to offspring

Answer 8

Mendel

Question 9

What does the principle of dominance state?

Answer 9

• Some genes are always expressed (dominant) others are recessive

Question 10

The expressed trait is the?

Answer 10

• Phenotype

Question 11

What is the genotype?

Answer 11

• The underlying genes that govern the train

Question 12

Brown eyes, dark hair & normal colour vision are ______ traits, expressed in the _________.

Answer 12

• Dominant

- Phenotype

Question 13

What are some recessive traits? When are they expressed in the phenotype?

Answer 13

• Blue eyes, baldness, colour blindness

- Expressed when paired with another recessive gene

Question 14

What is the difference between homozygous alleles and heterozygous alleles (single gene inheritance)?

Answer 14

• Homozygous alleles: parents have contributed similar genes for a trait (BB,bb)
• Heterozygous alleles: parents have contributed different versions. Phenotype of child often determined by dominance

Question 15

When traits are determined by a number of genes (I.e height, weight) this is known as _________ inheritance

Answer 15

• Ploygenic

Question 16

When the dominant gene does not completely suppress the recessive gene- it blends, this is called

Answer 16

• Incomplete dominance

Question 17

What is co- dominance?

Answer 17

• When both genes are dominant and thus, both expressed in phenotype ex: blood type- dad has A, mom has B, child will get both

Question 18

Inherited disorders and chromosomal abnormalities are examples of ________ disorders

Answer 18

• Genetic

Question 19

Inherited disorders can result from both ______ and _______ alleles

Answer 19

• Dominant

- Recessive

Question 20

How can chromosomal abnormalities result?

Answer 20

• Myotic division

- Teratogens

Question 21

This dominant, hereditary disorder is characterized by nervous system degeneration, uncontrollable muscle movements, and death. It is a result of an abnormality of chromosome 4

Answer 21

• Huntington’s disease

Question 22

What are some characteristics of PKU?

Answer 22

• Inability to metabolize the amino acid phenylalanine due to lack of liver enzyme (toxic in CNS), intellectual disability, periodic convulsions & seizures may occur
• ppl with this are put on a low- protein diet
• screened at birth and 2 weeks post birth

Question 23

This is a fatal nervous system disease in which the body cannot metabolize fats very well due to the absence of the enzyme hexosomindase
- it effects chromosome 15

Answer 23

• Tay- Sachs disease

Question 24

This refers to the compete set of genes that an organism processes

Answer 24

Genome