Genetics midterm Flashcards Preview

Genetics Simplified > Genetics midterm > Flashcards

Flashcards in Genetics midterm Deck (63)
Loading flashcards...
1
Q

What was the “one gene hypothesis,”? Did it turn out to be correct?

A
  • Hypothesis: one gene=one protein

- Not correct, 1 gene codes for at least 10 proteins

2
Q

SNPs and other mutations were thought to be the sole cause of human variation, was this assumption correct?

A

No

humans have minimal gene variation compared to other mammals

3
Q

How much of the Human Genome is Protein Coding? How much is RVS

A
  • 4% Protein Coding

- 9% Retroviral

4
Q

In what people and country does most of the variability in the human genome still reside

A

San Bushmen people of East Africa

5
Q

How are mitochondrial DNA and Y chromosomes DNA different and how are they used in migration studies?

A

Comparing the mtDNA “age” with the number of mutations on the Y chromosome, the time frame and direction of migration can be determined

6
Q

What did the story about kook and her kitty cat suggest about human behavior

A

LOOK UP

7
Q

What are the three main problems with trying to determine the cause vs correlation in genetic disease and genetic studies like GWAS

A
  • Association was found by CHANCE
  • Association is result of biased in study (LINKAGE disequilibrium)
8
Q

Know the 5 points of control and how they work!

A
  1. CHROMATIN STAGE:
    - regulated by methylation of cytidine
    - histone modification via acetyl group addition to promote transcription
    - exon shuffling
  2. Transcription:
    - Promoters and enhancers upstream (TATA and CCAAT)
    - Transcription factors
  3. Translation:
    - 5’ cap and 3’poly(A)tail added to mRNA
    - Introns removed eons spliced
  4. Post Translational control into cytoplasm:
    - leave via exportins
    - enter via inportins
  5. Post translational modification:
    - addition of functional groups
    - phosphorylation
    - most important regulation step
9
Q

TATA and CCAAT are examples of what?

A

promoters

10
Q

What is exon shuffling?

Which part exon or intron remains as a section of mRNA

A
  • Exons
  • Exon shuffling is when two or more exon from different genes can be brought together or the same exon is duplication to crease a new exon-intron structure
11
Q

What is the role of enhancers?

A

a short region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene occurs

12
Q

3 main molecular groups that modify histone and cause epigenetic effects?

A
  • Acetyl
  • Methyl
  • Phosphate
13
Q

Which epigenetic marker can attach to DNA directly?

A

Acetyl

14
Q

When looking at a cartoon or ideogram of a chromosome, how can you tell the locus from the gene? (essentially know the abbreviations for each. For instance is EPO the gene or the locus?

A
  • Locus: begins with p/q

- Gene: named with an acronym or something not beginning with p/q

15
Q

What are DNA Marker Alleles? Are they necessarily involved in transcription or biologically active?

A

Any gene or allele that is associated with a specific chromosome can be used to identify the chromosome or locate other genes or alleles

-They are not necessarily directly involved in transcription or biologically active

16
Q

What is Geneotype?

What is Phenotype?

A
  • Genotype: combination of alleles a person has

- Phenotype: any observable train, expressed by genotype

17
Q

What is the disease characteristic and pedigree characteristic of autosomal dominant

A

Locus is on an autosomal chromosome and only one mutant allele is required for expression of the phenotype

18
Q

Review your pedigrees

A

Just do it

19
Q

What is the disease characteristic and pedigree characteristic of autosomal recessive

A

The locus is on an autosomal chromosome

-both alleles must be recessive to express the phenotype

20
Q

What is the disease characteristic and pedigree characteristic of x-linked recessive

A

The locus is on the x chromosome

  • both alleles must be a recessive allele to expresses the phenotype in females
  • only one must be present in males
21
Q

What is the disease characteristic and pedigree characteristic of X-linked dominant?

A

The locus is on the X chromosome and only one mutant allele is required for expression of the phenotype in females

22
Q

What is the disease characteristic and pedigree characteristic of mitochondrial inheritance

A

The locus is on the mitochondrial chromosome

23
Q

What are the characteristics of X-linked Dominant Diseases?

A

X-linked dominant diseases are twice as common in females than males

24
Q

Can X-linked Dominant diseases be transmitted from father to son?

What about from father to daughter?

A
  • A father can not transmit to his son (he donates the Y)

- Father can donate to his daughter (gives the X)

25
Q

Why can males get X-linked recessive diseases with just one mutated allele?

A

-Males only have one X chromosome

26
Q

What is the difference between a missense mutation and a nonsense mutation?

A
  • Missense: Single base change in the gene that leads to a change in the codon that encodes for one amino acid
  • Nonsense: a base change that results in a “stop” codon- a short and completely inactive protein/enzyme
27
Q

What is the difference between gain-of-function and loss-of-function mutation and is one necessarily less troublesome than the other?

A

Loss-of-function: causes a vital or protective protein to become non-functional in the cell

Gain-of-function: occurs when either a completely new enzyme is produced in a cell, or more commonly, the enzyme is over produced

28
Q

Why is consanguinity important in clinical medicine, even though it is rare among Americans

A

“kissing cousins” can give rise to genetic disease (recessive)

29
Q

Why is it called Fragile X Syndrome, and what determines it’s severity?

A

Most common cause of mental retardation due to a number CGG repeats
-which determines severity

30
Q

What is the epigenetic significance of X chromosome inactivation

A
  • females only have one X chromosome active

- inactivated one is called a bar body

31
Q

Do Barr bodies form when autosomal chromosomes are imprinted (AS and PWS)

A

Yes

Imprinting is when one of the chromosomes are shut down either from mom or dad

32
Q

What is the general clinical characteristic of inherited mitochondrial disease?

A
  • It is only passed through females
  • Leads to neuropathies and myopathies
  • always affects the small motor muscles first
33
Q

What is the difference between the following:

  • Penetrance
  • Incomplete penetrance
  • Variability
A
  • Penetrance: the degree to which the phenotype is expressed
  • Incomplete Penetrance: some people have the genotype but do not express the phenotype

-Variability:
how “bad” the disease is when it is expressed

34
Q

What is recurrence risk (RR) and how is it calculated

A
  • The likelihood that a trait or disorder present in one family member will occur again in other family members in the same or subsequent generations
  • Calculate it by multiplying the penetrance by 25%(AR) or 50%(AD)
35
Q

What is pleiotropy?

Is Marfan Syndrome an example?

A
  • Pleiotropy: a single mutation that affects multiple organ systems
  • YES it is an example of AD mutation
36
Q

What is anticipation?
-What does it imply will occur in each subsequent generation of a family carrying mutation causing a disease characterized by anticipation?

A
  • A pattern of inheritance in which individuals in the most recent generations of a pedigree develop a disease at an earlier age or with greater severity than do those in the earlier generation
  • usually due to gradual expansion of trinucleotide repeat polymorphisms within or near a coding gene.
37
Q

How are the bands of a chromosome stained for a karyotype?

What are the three types of bands?

A
  • Glemsa staining
  • Done via 5 fluorescent probes that hybridize differently to different sets of chromosomes
  • Positive
  • Negative
  • Variable
38
Q

How many BP’s have to be involved in a deletion or duplication to be grossly detectable on a karyotype without using special immunofluorescent stains?

A
  • Need >4Mb to be seen

- FISH detects less than 4Mb

39
Q

What is the main cause of NUMERICAL chromosome abnormalities?

A

Meiotic nondisjunction due to spindle fibers behaving badly

40
Q

What disease is Trisomy 21

A

Down’s Syndrome

41
Q

What disease is Trisomy 18

A

Edwards syndrome

  • poor prognosis
  • AVSD, PDA
  • hand food and mouth malformations
  • low set ears and microganthia
42
Q

What disease is Trisomy 13

A

Patau Syndrome

  • polydactyly
  • cleft lip/palate
  • microphtalmia (small eyes)
  • microcephaly
  • cardiac and renal defects
  • poo prognosis
43
Q

Why aren’t there any autosomal monosomes listed in the slides?

A

They are incomparable with life

44
Q

What are the the characteristics and Karyotype numbers for Turners syndrome

A
  • only monosomy consistent with life
  • Karyotype 45/X, 46XX and 47XXX
  • short stature
  • ovarian dysgenesis -neurocognitive problems
45
Q

What are the characteristics and Karyotype numbers for Klinefelter’s Syndrome

A
  • Karyotype : 47XXXY
  • Males predominantly effected
  • Presence of both sex organs is rare
  • Hypogonadism
  • Low testosterone/high FSH and LH rather than testicular atrophy
  • Males tend to be weaker and grow taller than average
  • Males have larger breasts, wide hips and most noticeable during puberty, often look normal as adults
  • Often infertile
46
Q

What are the characteristics and Karyotype numbers for Alien 3 Syndrome?

A
  • 47XYY
  • Normal Phenotype and occurs during abnormal separation of chromosomes during anaphase II resulting from nondisjunction leaves sperm cell with extra Y
47
Q

Through which mechanism is the philadelphia chromosome formed?

What disease is it associated with and what is its significance?

A
  • Formed via Reciprocal Translocation
  • chromosome 9 and 22
  • If it occurs on hematopoietic cells it can result in Chronic myelogenous leukemia
48
Q

What are the Philadelphia chromosome numbers?

A
  • t(9;22)
  • 5(15;17)
  • (t(8;14)
49
Q

Can partial monosomes occur?

A

Yes

50
Q

What disease is this Karyotype??
-46,XX,-14,

-46,XY,-14,

A

Down Syndrome caused by partial monosomy read?

51
Q

Cri-du chat results from what abnormality?

Does the patients voice improve as they age?

A

-results from deletion on short arm of chromosome 5

  • abnormal larynx development “cry of cat”
  • most develop normally after age 2
52
Q

How did Angelman Syndrome and Prader-Willi Syndrome (PWS_ work?

What is their significance in the development of the field of epigenetic?

A

Angelman syndrome:

  • micro deletion of maternal 15
  • causing happy children who are ataxic and epileptic

Prader-Willi Syndrome:

  • Microdeletion in paternal chromosome 15
  • child who intensely craves food
  • Floppy baby
53
Q

What is a ring chromosome, and what is its significance?

A
  • forms when a deletion occurs on both tips of a chromosome and the remaining chromosome ends fuse together
  • results in monosomy
54
Q

What are the three karyotypes for a ring chromosome and what do they mean?

A
  • R-Ring Chromosome
  • T-Translocation
  • I-Isochromosome
55
Q

A chromosome that divides along the axis perpendicular to its normal axis of division that results in two copies of the chromosome but no copy of the other is called what?

A

Isochromosomes

56
Q

Are Isochromosomes seen in autosomes in live patients?

A

No

-incompatable with life, most observed in live births involving X chromosome

57
Q

In the overkalix studies it was found that nutritional influences and their subsequent epigenetic markers could be transmitted to future generations:

When was it thought that these epigenetic effects are imprinted onto the fetus of women

A
  • Females In Utero

- Males Late Childhood

58
Q

Who was George Price and what was his contribution to genetics?

A

-Population geneticist who wrote equation that described evolution,natural selection, game theory equation

59
Q

In the overkalix studies it was found that nutritional influences and their subsequent epigenetic markers could be transmitted to future generations:

When can the influences be acquired for transmission by males?

Are these the only times epigenetic effects can be acquired?

A
  • During gamete formation

- Not the only time

60
Q

What is the major reason gene therapy did not work out?

A
  • Infecting gene via virus into humans can be challenging and potentially harmful
  • Problems with integrating therapeutic DNA into the genome and then rapidly dividing nature of many cells prevent gene therapy form achieving any long-term benefits
61
Q

What inhibits gene expression or translation by neutralizing targeted mRNA

A

iRNA

Interference RNA:

62
Q

Can iRNA be passed to subsequent generations

A

Yes

63
Q

What are Knock-down studies?

How do they work?

What do knock-down studies tell you about a gene?’’
What is the most effective modality for performing knock-down studies?

A

Studies that use RNA to see if it can be used for large-scale screens that systematically shut down each gene in the cell, which can help identify the components necessary for a particular cellular process or an event such as cell division

-used to test the effect of mutated genes