Principles Of Genetic Inheritance

Question 1

What is the region at the end of a chromosome that is meant for stability

Answer 1

Telomere

Question 2

Contrast Metacentric vs submetacentric vs acrocentric chromosomes

Answer 2

Metacentric- have a centromere in the center such that both arms are the same length

Submetecentric- has a centromere in the center such that one arm (p) is slightly shorter than the other (q)

Acrocentric- has a chromosome severely off set from the center such that there is one really short p arm and one really long q arm

Question 3

_____ is a x-inactivation in which one X chromosome is in activated. It happens early in development and the inactivated X is called a Barr body

Answer 3

Lyonization

Question 4

_____ is a condition in which cells from a patient have different genotypes and karyotypes because the different cells in the body have different arrangement or numbers of chromosomes

Answer 4

Mosaicism

Question 5

Stem cells undergo mitosis, but divide asymmetrically, resulting in one _____ cell and one _______ cell

Answer 5

One stem cell, and one daughter cell

Question 6

What is the big difference between mitosis and meiosis cell division

Answer 6

Mitosis results in 2 identical daughter cells that are diploid

Meiosis results in 4 non identical daughter cells that are haploid

Question 7

What is responsible for producing new combination of genes in meiosis

Answer 7

Homologous recombination

Question 8

Are homologous chromosomes identical

Answer 8

NO

Question 9

_____ changes the sequence of alleles that are passed from generation to generation.

Answer 9

Mutations

Question 10

T/F De novo mutations are solely hereditary

Answer 10

False

They can be hereditary or somatic

Question 11

In meiosis there is one round of DNA replication and two rounds of nuclear division. The first separation is of _____ and the second separation is _______

Answer 11

1. Homologs
2. Sister chromatids

**Meiosis reduces the genetic material

Question 12

What are two ways meiosis creates diversity

Answer 12

1. Random segregation of homologs

2. Homologous recombination

Question 13

Cells with a normal number of chromosomes (haploid gametes or diploid somatic cells) are called what

Answer 13

Euploid cells

Question 14

_____ is the presence of a complete set of extra chromosomes in a cell (often seen in plants)

Answer 14

Polyploidy cells

Question 15

____ are cells with missing or additional individual chromosomes (monosomy, trisomy)

Answer 15

Aneuploidy cells

Question 16

45, XO karotype
-females with short stature, ovarian hypofunction, premature ovarian failure, infertile, CV defects, low hairline on neck, webbed neck, normal intelligence

Answer 16

Turners Syndrome

Question 17

47, XXY karotype

• limited symptoms
• varying degree of cognitive/social/behavioral difficulties,
• primary hypogondaism
• small testes
• gyneomastia (male breasts)
• tall stature
• infertile
• can have a variable number of extra chromosomes

Answer 17

Klienfelter syndrome

Question 18

47, XX +21

• most common
• increased risk of nondysjunction with maternal age
• can also occur due to translocation 46, XX (14:21) (q10;10)+21
• can be mosaic

Answer 18

Down Syndrome

Question 19

47, XX +13
-severe developmental abnormalities
-most perinatal death within 1 week
(13% live births live to 10 y.o.)

Answer 19

Patau Syndrome

Question 20

47, XX +18
-abnormal development
-most perinatal death within 1 year
(10% of live births survive to 10 y.o.)

Answer 20

Edwards Syndrome

Question 21

Explain Robertsonian Translocation

Answer 21

A robertsonian translocation is when two acrocentric chromosomes q arms combine to make “one”chromosome with the essential genes of two chromosomes. They can possibly pass on a robertsonian translocation and a normal chromosome and the child will result with an extra chromosome (trisomy)

Question 22

What are the acrocentric chromosomes

Answer 22

13, 14, 15, 21, 22

Question 23

What is genomic imprints

Answer 23

Imprinting is essentially gene silencing through methylation of the 5’ region of a gene or chromatin condensation

Question 24

When do epigenetic imprints reset for somatic and germ cells?

Answer 24

Somatic cell epigenetics last a lifetime

Germ cells are reset during meiosis, when imprints are erased and new ones are set

Question 25

What two diseases are a result of genomic imprinting (silencing of one parental chromosome)

Answer 25

Prayer-willi And Angelmans syndrome

Question 26

What are diseases caused by nondisjunction

Answer 26

``` Klienfelter Down syndrome Patau syndrome Edwards syndrome Turner syndrome ```

Question 27

Deletion of a region on chromosome 15 of the parental chromosome causes ____

Answer 27

Prader-Willi syndrome -causes short stature, hypotonia, small hands/feet, obesity, mild - moderate intellectual disability

Question 28

Deletion of region of chromosome 15 of the maternal chromosome causes ______

Answer 28

Angelmans Syndrome -severe intellectual disability, seizures, ataxic gait

Question 29

What is related to both non-disjunction and genomic imprinting? Two chromosomes are inherited from the same parent and they have parent-specific imprinting meaning only two chromosomes are expressed but they are both from the same parent

Answer 29

Uniparental disomy Can cause both Prader Willi and angelmans because only one parent is expressing chromosome 15

Question 30

Law of segregation vs law of independent assortment

Answer 30

Segregation says you can either be tall or short (1 dominant gene for that trait) IA- says you can be tall and wrinkly or tall and non wrinkly (different genes for different phenotypes are independently assorted )

Question 31

What is an example of someone with a distinct genotype on exhibiting one single phenotype

Answer 31

Cystic fibrosis

Question 32

What is an example of individuals with the same genotype having multiple different phenotypes (pleiotropy)

Answer 32

PKU

Question 33

What is pleiotropy

Answer 33

When one gene influences two or more seemingly unrelated phenotypic traits

Question 34

What is the first diagnosed person in a pedigree called

Answer 34

Proband (propositus): | Denoted by an arrow in a pedigree

Question 35

Percent chance of autosomal dominant and recessive, and x linked recessive and x linked dominant appearing in a generation?

Answer 35

Dominant- 50% - postaxial polydactlyl Recessive- 25% -albinism X-linked recessive - duchenne muscular dystrophy X linked -dominant (non carriers) - hypophosphatemia [causes rickets]

Question 36

What is consanguinity

Answer 36

First cousin mating

Question 37

The frequency a gene manifests itself is _____

Answer 37

Penetrance

Question 38

If someone with a mutation and do not develop the features of the disorder then the diseases is said to have ____

Answer 38

Reduced penetrance -ex: retinoblastoma (autosomal dominant with 90% P)

Question 39

___ is the range of phenotypes that can vary between individuals with a specific genotype

Answer 39

Variable expressivity Ex: neurofibromatosis -neurofibromas cause spots that range in size and color and number

Question 40

A single disorder, trait, or pattern of traits caused by mutation in genes at different chromosomal loci/genes. Same phenotype from mutation on two different genes

Answer 40

Locus heterogeneity -ex: Osteogenesis imperfecta *brittle bones and mutations in collagen genes (c 7 and 17)

Question 41

When would you use the multiplication rule or addition rule of probability

Answer 41

Multiplication: -probability of a given outcome in multiple trials Ex: probability of having 3 girls 1/2 x 1/2 x 1/2 = 1/8 Addition: -probability of either one or another outcome Ex: probability of having 3 girls or three boys ? 1/8 + 1/8 = 2/8 = 1/4

Question 42

You can used Hardy Weinberg principle when you are given the incidence of a disease and you want to find population frequency or allele frequency

Answer 42

P + q = 1

Question 43

what has its own circular DNA - contains no introns - inherited solely by mother - mutation rate is 10x that of nDNA bc lack of DNA repair mechanisms and damage from free radicals released during OxPhos

Answer 43

Mitochondrial DNA (mtDNA) - encodes rRNA and tRNA and 13 polypeptides used in OxPhos - transcription takes place in the mitochondria independent of the nucleus

Question 44

Mitochondrial inheritance

Answer 44

*passed through the mother **IF mother is mutated/infected then every child gets infected/mutated mitochondria *but the degree of mutation is different for each infected individual therefore some may lead to mitochondrial disease and some may not (this is because mitochondria are distributed unequally)

Question 45

Traits in which variations are thought to be caused by combined effect s of multiple genes

Answer 45

Polygenic

Question 46

When environmental factors cause variation in the trait the term _______ is used

Answer 46

Multifactorial

Question 47

Multifactorial inheritance follows what pattern? If they do not follow the normal pattern then there is an underlying _____

Answer 47

Follow a bell shaped distribution in populations -underlying liability distribution. Some may have a threshold of liability where the disease is either present or absent. ***A result of polygenic traits. (Simultaneous influence of multiple genetic and environment factors)

Question 48

What type of inheritance is exhibited by muscular hypertrophy?

Answer 48

Multifactorial inheritance *men need less risk genes vs females (The least affected sex has a higher risk threshold and transmits the condition more often to the more affected sex)

Question 49

Explain the Recurrence Risks of multifactorial inheritance | **varies more greatly than single-gene diseases bc it is population based

Answer 49

- the recurrence risk is higher if more than one family member is affected - if the expression is severe in the proband, the reccurence risk is higher - the recurrence risk if higher if the proband is the less affected sex - the recurrence risk for the disease usually decreases rapidly in more remotely related relatives