Ch 22 Medical Genetics

Question 1

What are human traits determined by?

Answer 1

Both genetics and the enviroment

Question 2

Are diseases more likely in genetic relatives or in the general population?

Answer 2

Genetic relatives

Question 3

What is a monozygote?

Answer 3

An identical twin

Question 4

What is a dizygote?

Answer 4

A non identical twin

Question 5

Is a disease more likely to occur in momzygotes or dizygotes?

Answer 5

Monozygotes

Question 6

what is concordance?

Answer 6

The degree to which a disease is inherited. Calculated by dividing number of twins BOTH with disease over number of twins in which ONE has disease

Question 7

What is the concordance in diseases that are only associated with a single gene in idnetical twins?

Answer 7

100%

Question 8

What is concordance in dizygotic twins assuming one is HETEROYGOUS?

Answer 8

50%

Question 9

What is concordance for recessive diseases in twins?

Answer 9

25% assuming both heterozygous

Question 10

What are reasons that concordance would be lower than expected?

Answer 10

If incomplete penetrance occurs OR if one twin gets disease from mutation after fertilization

Question 11

Examples of Autosomal Recessive Disorders

Answer 11

Ablinism, ADD, and Cystic Fibrosis, Tay Sachs disease

Question 12

Characteristics of Recessive diseases

Answer 12

1) Affected offspring usually has two unaffected parents
2) two unaffected parents (heterozygotes) have 25% diseased children
3) Two affected individuals produce affected offspring

Question 13

Does gender affect recessive disease frequency?

Answer 13

NO equal in both genders

Question 14

Examples of Autosomal Dominant Disorders?

Answer 14

Huntingtons disease and Dwarfism

Question 15

Characteristics of Huntigntons?

Answer 15

1) affected offspring have one or more affected parents

2) Homo more effected that hetero individual

Question 16

Examples of Xlinked recessive diseases?

Answer 16

Hemophila A/B and muscular distrophy

Question 17

What are biochemical Assays used for?

Answer 17

To determine the enzymatic function of certain proteins that effect diseases
Ex: Hex A (enyzme that causes tay sachs

Question 18

What is Amniocentesis?

Answer 18

removal of amniotic fluid from embyo for karyotyping

Question 19

What is chorionic villus sampling

Answer 19

removal of small pieces of chorian (placenta)that are analyzed. Can be done earlier but poses greater risk for miscarriage

Question 20

What is preimplantation genetic diagnosis?

Answer 20

Conducted before pregnancy in vitro. Genetic testing of embryo by removing one of the two cells at 8 cell stage. Called embryo biopsyor blastomere biopsy

Question 21

What is a prion? And who does it effect?

Answer 21

proteinaceous infectious particles that alter protein function post-translationally.
Causes nerodegenerative diseases in cows

Question 22

What do pRp proteins bind to?

Answer 22

Copper ions with high affinity

Question 23

What are the two prion conformations?

Answer 23

Normal PRPc and abnormal PRPsc

Question 24

How is the abnormal form of PRP attained?

Answer 24

By eating bad meat or by being infected by individual with PRPsc or by spontaneous transformation

Question 25

Why is PRPsc so bad?

Answer 25

Because the prescence of the abnormal PRP causes normal PRPc to convert to PRPsc

Question 26

Cancer caused by what?

Answer 26

Uncontrolled cell division

Question 27

Carinogen

Answer 27

Enviromental causes of cancers

Question 28

Characteristics of Cancer include?

Answer 28

1) usually originates in single cell 2) usually starts with benign growth 3) progresses to malignant over time 4) invasive and metastatic

Question 29

How can viruses cause cancer?

Answer 29

Carry viral oncogenes into the cell

Question 30

Transformation

Answer 30

Process of changing normal cell to malignant cell

Question 31

What are ACV's?

Answer 31

Type of virus capable of transformation

Question 32

What is a gene that promotes cancer called?

Answer 32

An oncogene

Question 33

The normal cell cycle is regulated by what?

Answer 33

polypeptide hormones known as growth factors

Question 34

Proto Oncogene

Answer 34

Normal gene with capability of becoming oncogene

Question 35

How do proto oncogenes become oncogenes?

Answer 35

1) Amount of encoded protein greatly increased 2) protein structure altered resulting in overexpresion 3) Protein expressed in cell type where it is not normally expressed

Question 36

What is the RAS protein?

Answer 36

A GTPase that converts GTP to GDP+pi

Question 37

What is the effect of RAS becoming an oncogene?

Answer 37

1) decrease ability of RAS to transform GTP 2) Increase the rate of exchang of bound GDP for GTP * BOth result in more bound GDP keeping signaling pathway turned ON and cell division increasing

Question 38

How to change proto oncogene to a full blown oncogene?

Answer 38

1) Missense mutation causes abnormal function 2) Amplification 3) Viral Integration 4) Chromosomal Translocation

Question 39

What do tumor supressor genes do?

Answer 39

prevent proliferation of cancer. If inactivated by mutation, chances of cancer increase

Question 40

What is p53 gene?

Answer 40

A tumor supressor gene that senses DNA damage | * 50% of cancers associated with mutation in this gene

Question 41

What are the three things p53 does?

Answer 41

1) repair cell damage 2) start apoptosiis of bad cells 3) arresting cell cycle

Question 42

How does apoptosis work?

Answer 42

protease called capspaces act as exuctioners of cells by digesting things like microtubles

Question 43

How is maintenance of the genome accomplished?

Answer 43

Checkpoint proteins and DNA repair proteins

Question 44

How do checkpoint proteins work?

Answer 44

prevent cell division when damaged DNA is detected | Prevent accumulation of cyclin CDK complexes that promote cell division

Question 45

What do G1 and G2 checkpoints do?

Answer 45

look for DNA damage and if found prevent formation of cyclin cdk complexes

Question 46

What does M checkpoint do?

Answer 46

sense if a chromosome is not attached to spindle correctly