Lecture 29. Mendelian Inheritance

Question 1

What is a gene?

Answer 1

A unit of inheritance, a section of DNA sequence encoding a single protein

Question 2

What is a genome ?

Answer 2

The entire set of genes in an organism

Question 3

What is an allele ?

Answer 3

Two genes that occupy the same position on homologous chromosomes and that cover the same trait

Question 4

What is the locus ?

Answer 4

A fixed location on a strand of DNA where a gene or one of its alleles is located

Question 5

What does the term homozygous mean ?

Answer 5

Having identical genes (one from each parent) for a particular characteristic

Question 6

What does the term heterozygous mean ?

Answer 6

Having two different genes for a particular characteristic

Question 7

What does the term dominant mean ?

Answer 7

The allele of a gene that masks or suppresses the expression of an alternate allele; the trait appears in the heterozygous condition

Question 8

What does the term recessive mean ?

Answer 8

An allele that is masked by a dominant allele, it does not appear in the heterozygous condition only in the homozygous

Question 9

What is the genotype ?

Answer 9

The genetic makeup of an organism

Question 10

What is the phenotype ?

Answer 10

The physical appearance of an organism (genotype + environment)

Question 11

What is a monohybrid cross ?

Answer 11

A genetic cross involving a single pair of genes

Question 12

What does P stand for ?

Answer 12

Parental generation

Question 13

What does F1 stand for ?

Answer 13

First generation offspring from a genetic cross

Question 14

What does F2 stand for ?

Answer 14

Second generation of a genetic cross

Question 15

What did Mendel work with ?

Answer 15

Pure lines of peas

Question 16

Prior to Mendel what was heredity and offspring regarded as ?

Answer 16

Heredity was regarded as a blending process and the offspring were essentially a dilution of the different parental characteristics

Question 17

What was Mendel the first biologist to do ?

Answer 17

To use maths to explain results quantitatively

Question 18

What did Mendel predict ?

Answer 18

1. The concept of genes
2. That genes occur in plants
3. That one gene of each pair is present in the gametes

Question 19

What were the 7 traits Mendel examined ?

Answer 19

1. Round or wrinkled
2. Yellow or green
3. Purple or white petals
4. Inflated or pinched ripe pods
5. Green or yellow pods
6. Axial or terminal flowers
7. Long or short stems

Question 20

What are the two types of alzheimers ?

Answer 20

1. Genetic

2. Sporadic

Question 21

What can alzheimer’s caused by ?

Answer 21

Build up of plaque (amyloid)

Question 22

What is Mendel’s principle of dominance ?

Answer 22

Independent segregation of 2 alleles

Question 23

What is Mendel’s principle of segregation ?

Answer 23

Independent assortment of 2 characters

Question 24

What is Mendel’s law of dominance ?

Answer 24

One factor in a pair of traits dominated the other in inheritance unless both factors in the pair are recessive

Question 25

What gene is effected in age related muscular degeneration and what is its position ?

Answer 25

1. Rhodopsin gene | 2. 3q

Question 26

How would you find the combined probability of two traits occurring, for example yellow and round ?

Answer 26

By multiplying the probability of yellow occurring by the probability of round occurring

Question 27

What is linkage ?

Answer 27

Tendency of genes from the same chromosome to remain together when they enter the gamete

Question 28

What is recombination ?

Answer 28

The appearance of new combinations of alleles

Question 29

What is termed a Mendelian disease ?

Answer 29

When mutations in a single gene cause a disease

Question 30

What are some examples of Mendelian disorders ?

Answer 30

1. Cystic Fibrosis 2. Leber's congenital amaurosis 3. Huntington's disease 4. Haemophilia

Question 31

What type of inheritance does Huntington's disease have ?

Answer 31

Autosomal dominant inheritance

Question 32

When may inheritance of characters by a single gene deviate from simple Mendelian patterns ?

Answer 32

1. When alleles are not completely dominant or recessive (dosage sensitivity) 2. When a gene has more than two alleles 3. When a gene produces multiple phenotypes

Question 33

What were Alfred Sturtevant ideas ?

Answer 33

1. Proposed that percentage recombinants could be used to measure distance between genes 2. Constructed the first genetic map

Question 34

In humans, how many chromosomes do somatic cells have ?

Answer 34

46

Question 35

In humans, how many pairs of chromosomes do somatic cells have ?

Answer 35

23

Question 36

What does the term diploid mean ?

Answer 36

Two versions of each gene

Question 37

What does the formation of germ cells require ?

Answer 37

Require a reduction division or meiosis

Question 38

What is the process of meiosis ?

Answer 38

Homologous chromosomes pair up at metaphase 1, and each segregates into a different germ cell