Transmission In Genetics

Question 1

What does monogenic mean?

Answer 1

A Neuro genetic disease with a single gene cause

Question 2

What percentage of Alzheimer’s disease is monogenic

Answer 2

1%

Question 3

What percentage of Parkinson’s disease is monogenic

Answer 3

10%

Question 4

What percentage of motor neurones disease is monogenic

Answer 4

5%

Question 5

What was mendels work and when did he publish it

Answer 5

Published in 1865
- bred peas that gave rise to similar characteristics in every generation
- identified 7 characteristics that were consistent in generation after generation of self-fertilisation
- the parental lines of peas could be considered pure-breeders

Question 6

What characteristics of the peas did Mendel study

Answer 6

Colour and texture of peas
Colour of pea pods and flower
Height of the plant

Question 7

Outline Mendels principle of independent assortment

Answer 7

-genes get sorted into gametes independently
-second generation all dominant
Third generation is in a 9:3:3:1 ratio

Question 8

What was mendels 1st law

Answer 8

Law of dominance and uniformity- some alleles are dominant while others are recessive; an organism with at least one dominant allele will display the effects of the dominant allele

Question 9

What was mendels 2nd law

Answer 9

Law of segregation- during gamete formation, the alleles for each gene segregated from each other so that each gamete carries only one allele for each gene

Question 10

What was mendels 3rd law

Answer 10

Law of independent assortment- genes of different traits can segregate independently during the formation of gametes

Question 11

What was mendels chromosomal theory of inheritance in the 1900

Answer 11

Meiosis cell division that occurs in germ cells- in the process of making sperm and eggs (pollen and ovules in plants)
-as egg cells matured, there comes a point where chromosomes numbers are reduced in half

Question 12

What is the concept of the germ line

Answer 12

Cells that can pass genetic material to the next generation
-includes haploid sperm and egg cells (gametes) and all the diploid precursor cells from which they arise by cell division, going all the way back to the zygote

Question 13

What are non-germ line cells known as

Answer 13

Somatic cells

Question 14

How many cells does meiosis result in?

Answer 14

4 haploid cells

Question 15

Outline random assortment of homologous chromosomes in meiosis

Answer 15

-for each chromosome in metaphase 1, homologous chromosomes line up at the equator
-orientation of pairs of chromosomes is random
-random assortment of chromosomes into gametes

Question 16

What does independent assortment in meiosis provide?

Answer 16

Independent assortment of maternal and paternal homologous chromosomes during meiosis provides variation in the genetic composition of sperm or eggs

Question 17

How can the risk of being affected by disease for family members of an affected individual be predicted

Answer 17

-screening
-treatment

Question 18

How can the risk of being a carrier of disease for family members of an affected individual be predicted

Answer 18

-risk to the unborn child
-reproduction choices

Question 19

Is the sickle cell allele recessive or dominant

Answer 19

Recessive allele

Question 20

How many genes does the X chromosome have

Answer 20

800

Question 21

How many genes does the Y chromosome have

Answer 21

70

Question 22

Definition of complete penetrance

Answer 22

All individuals have the phenotype

Question 23

Definition of incomplete penetrance

Answer 23

Individuals a genotype may or may not. Develop a phenotype

Question 24

Outline epistasis

Answer 24

Interaction between genes, whereby the protein product of one gene interferes with the expression of another gene

Question 25

Definition of epistatic gene

Answer 25

A gene that masks the phenotypic effect of another

Question 26

What are missense mutations

Answer 26

Codes for a different amino acid
-the synthesis of an altered protein

Question 27

Outline missense non-conservative substitutions

Answer 27

Amino acid is chemically dissimilar- has a different charge the structure oft he protein will be altered

Question 28

Outline missense conservative substitutions

Answer 28

Some single base-pair substitutions resulting the replacement of an amino acid that is chemically similar.

Question 29

Outline nonsense mutations

Answer 29

-Formation of a stop codon will result in premature termination of translation of a peptide chain
-premature stop codon may lead to expression of a truncated protein. However usually the mRNA is degraded by nonsense mediated decay, so NO protein is made

Question 30

What is nonsense mediated decay

Answer 30

Nonsense mediated decay is a form of RNA surveillance that is believed to protect the body from the possible consequences of truncated proteins interfering with normal function

Question 31

What does InDel usually result in?

Answer 31

Premature stop codon downstream of the mutations; this manny result in a truncated protein

Question 32

How to identify disease genes in humans

Answer 32

coding region can be sequenced from cDNA, or the whole genome can be sequenced

Question 33

How was the mutations for Charcot-Marie tooth identified?

Answer 33

Exome sequencing (sequencing cDNA) using 2nd generation sequencing (illumina sequencing)