10/16 genetics

Question 1

what is the typical inheritance of mitochondrial diseases?

Answer 1

they are inherited from the mother and the mother will pass it on to all of her offspring (though incomplete penetrance is posible.

Question 2

what are some importanct features of mitochondrial genetic mutations?

Answer 2

inheritance is maternal.

Mutation rate is high.

Question 3

why would the mitochondria have such a high mutation rate?

Answer 3

• repair is not as efficient.

- There are a lt of oxidative species in the mitochondria.

Question 4

what is heteroplamsy in genetic?

Answer 4

mitochondrial mosaicism within cells!

Question 5

why would we see expression of some mitochondria mutations in some cells but not all the cells of an individual

Answer 5

Heteroplasmy is very common

Question 6

what are some common diseases that see mitochondrial mutation genetics

Answer 6

deafness
type 2 diabetes
alzheimer disease?
parkinson disease?
aging...

Question 7

what is somatic cell nuclear transfer?

Answer 7

healthy donar egg has the nucleus removed and the “mother’s” nucleus is put in and then that is used for IVF!

Question 8

what is the most common cause of pregnancy loss?

Answer 8

Chromosome abnormalitites

Question 9

what is the most common cause of intellectual disability?

Answer 9

Chromosome abnormalities.

Question 10

genetic term for multiple of “true number” of chromosome

Answer 10

Euploid

Question 11

23 chromosomes

Answer 11

Haploid

Question 12

46 chromosomes

Answer 12

diploid

Question 13

69 chromosomes

Answer 13

triploid

Question 14

92 chromosomes

Answer 14

tetraploid

Question 15

Genetic term for number of chromosomes that is not a multiple of the “true number”

Answer 15

Aneuploid

Question 16

One copy of a specific chromosome

Answer 16

Monosomy

Question 17

Three copies of a specific chromosome

Answer 17

Trisomy

Question 18

Compare How is the survivial for Monosomy of any chromosome to Trisomy

Answer 18

No survival for monosomy; but survival of trisomy is reletively common. it seems that it is better to have more than not have enough chromosomes

Question 19

how did we ever get a picture of the chromosomes?

Answer 19

use colchicine (spindle poison) to arrest the cells in metaphase, and use a hypotonic solution to swell and break the cell and visualize the chromosomes.

Question 20

what is Giemsa stain?

Answer 20

It is G-banded staining of chromosomes that gave them stripes by the amount of A,T that the different sections have

Question 21

the image of the chromosomes of an individual by G-banding staining

Answer 21

Karyogram

Question 22

Where are the genes in G-banded staining

Answer 22

in the light staining reagions (A,T poor regions)

Question 23

the effects of having an extra copy of all of the chromosomes

Answer 23

Occipital and other skull bone problems
hypercesis
heart defects

Lethal in a short time after birth

Question 24

How could we get triploid genotypes?

Answer 24

two sperm cells could fertilize the egg.

could also see egg cells with diploid (myotic failure)

Question 25

How do Triploids usually give us a good example of imprinting effect?

Answer 25

Dad source of triploidy: large fetus | Mom source of triploidy: small Fetus

Question 26

what are some of the major features seen in Down Syndrom?

Answer 26

``` Intellectual disability Congenital heart defects reduced stature; char. facial appearance increased risk of leukemia increased risk of repiratory infections neurohistopathology of alzheimer disease by age 40 (amyloid plaques) ```

Question 27

why would down syndrome patients develop alzheimer by 40 years old?

Answer 27

Gene 21 gives beta-amyloid precursor protein gene and the over production of this probably leads to amyloid plaques!

Question 28

what are the facial features of Down syndrome?

Answer 28

``` Strabismus large tounge and somewhat protrude epicanthic fold by the nose and the eye brushfield spots in the iris that gives it a speckled apearence upslanting palpebral fissures Small ear and folded ear ```

Question 29

Hypoplastic ear, and folding of the ear....

Answer 29

h

Question 30

what are the had features of D. Syndrom?

Answer 30

Single transverse palmer crease | single flexion crease in the inside of the finger.

Question 31

how is the survival of Down syndrom?

Answer 31

the median age of survival is about the mid Fifties.

Question 32

What is the key in the process of developing Down Synderom?

Answer 32

nondisjunction where we have a failure in miosis I or Miosis II where the chromosomes don't seperate and you get a monosomic or a trisomic gamete.

Question 33

what causes the non-disjuction that leads to down syndrome?

Answer 33

the only thing that we have been able to coorilate to the occurance of D. syndrome is age of the mother. dramatic increase in risk after 35!

Question 34

why would there be a large increase in the occurance of D. syndrome with an older mother

Answer 34

the microtubule and the cohesion proteins that are in the eggs tend to degrade over time.

Question 35

how do single gene defect rates and trisomy rates differ for paternal genes?

Answer 35

the father's age does not affect the rate of trisomy but it does effect the single gene mutation rate greatly!

Question 36

why would you have an increased risk of a second child with down syndrome if a mother has one?

Answer 36

germ line mosaisism where the genes of multiple eggs have trisomy

Question 37

what is the recurrence risk for the offstpring of a down syndrome mother?

Answer 37

50% because half will have the trisomy in the eggs

Question 38

why would you see a smaller chance of down syndrome from D. syndrome mohters than predicted

Answer 38

75% of pregnancy is spontaniously lost

Question 39

how could you have a down syndrome that can be tested in the blood and not be present and be there in other tissue?

Answer 39

somatic mosaicism seen in 1-5% of cases. sometimes milder expression. Tissue-specific mosiacism may occur

Question 40

What could be a potential future cure of trisomey 21?

Answer 40

XIST inactivation. using the X inactivation gene and targeting it to the chromosome 21 and turning it into a non-transcriptional bar-body.

Question 41

What is the vitality of the mitochondrial genome?

Answer 41

The are important in the energy production in mitochondrial.