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Alex's Genetics > Lecture 20a > Flashcards

Lecture 20a Flashcards

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Biology 101 flashcards
1
Q

What are the 2 types of cancer cell migration?

A

Individual cell migration and Collective cell migration

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2
Q

Where is Individual Cell migration usually seen?

A

Normally seen in embryonic development where pre-neural cells migrate to form the peripheral nervous system and some other things.

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3
Q

What are the type types of Individual Cell migration?

A

Mesenchymal movement and Amoeboid movement.

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4
Q

What accounts for the difference between Mesenchymal movement and Amoeboid movement?

A

Different genes are involved in these 2 types of cell movement.

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5
Q

In Mesenchymal movement, how do the cells appear?

A

Cells appear elongated and ‘pointy’.

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6
Q

In Amoeboid movement, what are the cells and how do they appear?

A

They are cancer cells with rounded shape.

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7
Q

What is Collective Cell migration?

A

Groups of firmly interconnected cells migrating.

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8
Q

Where is Collective Cell migration normally seen?

A

Normally seen in wound healing and also in embryonic development.

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9
Q

In Collective Cell migration, what do leader cells do?

A

They secrete proteases to get past other cells and make space for invasion.

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10
Q

Define Probability.

A

The probability of an event is the chance that the event will occur in the future.

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11
Q

What is the equation for probability?

A

Number of times an event occurs / Total number of events

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12
Q

If we flip a coin 100 times, what is the probability for heads?

A

50 / (50+50) = 50%

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13
Q

In Genetics, what does the accuracy of the probability prediction depend on? What does a smaller sample size lead to?

A

The size of the sample.

Smaller sample = less accurate probability

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14
Q

With probability in Genetics, there is often deviation between _______________ and _____________ outcomes.

A

observed & expected

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15
Q

What is the cause of deviation between observed and expected outcomes?

A

Random sampling error

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16
Q

How does Random Sampling Error differ for large versus small samples?

A

Random sampling error is large for small samples and small for large samples.

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17
Q

What is the Sum Rule?

A

The probability that one event OR the other event of two mutually exclusive events will occur is the sum of their respective probabilities.

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18
Q

If you have a 14% chance of dying of cancer and a 17% chance of dying of heart disease, what is the sum of the probabilities?

A

14 + 17 = 31% chance of dying from cancer OR heart disease.

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19
Q

Genetically speaking, what is the Product Rule?

A

The probability of an outcome involving one gene AND another outcome involving another gene will occur at the same time is equal to the product of their respective probabilities.

Basically, this is the probability of two things happening at once.

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20
Q

A person has a 14% chance of dying of cancer. A couple had 3 children. What is the probability of ALL 3 offspring dying of cancer?

A

This is the product rule, because it is talking about ALL 3 children getting cancer (several events at once).

(0.14)(0.14)(0.14) = 0.0027 = 0.27%

Convert from percentage to decimal.

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21
Q

What percentage of cancers involve inherited (germ-line) mutations? What do these people have a predisposition to?

A

About 5-10%

People who have inherited such mutations have a predisposition to develop cancer.

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22
Q

What does Genetic Testing allow for with predisposition? In what aspect is it limited?

A

Genetic testing allows us to test for certain types of cancer predisposition, however, we can only do this for genes that we know exist.

23
Q

What do most inherited forms of cancer involve?

A

A defect in tumor-suppressor genes

24
Q

What is BRCA1?

A

A tumor-suppressor gene that encodes a repair protein.

25
Q

What do inherited BRCA1 null alleles predispose people to?

A

Many kinds of cancer with female breast cancer & ovarian cancer being the most common.

26
Q

T/F: BRCA1 is an example of Incomplete Penetrance.

A

True!

27
Q

What does Incomplete Penetrance mean?

A

People can have the mutation and be unaffected, but they could also have the mutation and be affected.

28
Q

What does the strength of the mutation depend on? Which is the strongest mutation?

A

How strong the mutation is depends on the mutation.

Null Allele = Strongest Mutation

29
Q

If an individual is Heterozygous for BRCA1, what does this mean?

A

Cell has one functional copy of BRCA1.

30
Q

If an individual has a loss of heterozygosity for BRCA1, what does this mean?

A

Cell has zero functional copies of BRCA1. One allele is the inherited mutation and the other allele was mutated or the whole chromosome was deleted/missing.

31
Q

Inherited _________ & ____________ mutations predispose to many kinds of cancer with breast cancer in women being the most common.

A

BRCA1 & BRCA2

32
Q

What is the risk of developing breast cancer in a lifetime for an average woman in the US?

A

About a 12% risk

33
Q

Women who have a BRCA1 mutation or BRCA2 mutation can have a ~____% risk of being diagnosed with breast cancer during their lifetimes.

What plays a role in this?

A

68

Genetic background and the nature of the mutant BRCA1 or BRCA2 alleles play a role.

34
Q

What are Hypomorphic Alleles? How do these compare to Null alleles?

A

These are mutant alleles that are NOT null alleles.

The probability of cancer is less with these than if you had a null allele.

35
Q

In what age group do we generally see breast cancers associated with a BRCA1 or BRCA2 mutation? Is it in one or both breasts?

A

Tend to develop in younger women and occur more often in both breasts than cancers in women without these genetic mutations.

36
Q

T/F: Inherited BRCA1 and BRCA2 mutations only predispose to breast cancer.

A

False! Also an increased risk of developing ovarian, colon, and pancreatic cancers, as well as melanoma.

37
Q

Men who have a BRCA2 mutation have a __________ risk of breast cancer than men who don’t —- about __%. This is ___ times greater than average.

A

higher, 8%, 80

38
Q

What would happen if both alleles inherited (from both parents) were BRCA1 or BRCA2 null alleles?

A

Early embryonic lethality

39
Q

What are 2 ways to test for normal-looking chromosomes before birth?

A

Amniocentesis and Chorionic Villus Sampling

40
Q

Describe Amniocentesis.

A

Amniotic (supernatant) fluid is withdrawn from the placenta using a syringe. The fluid is then plated to culture cells and several weeks later, karyotyping is performed.

41
Q

Describe Chorionic Villus Sampling.

A

Chorionic villi are derived from the fertilized egg and karyotyping is performed in the SAME DAY.

42
Q

At what stage of development does Amniocentesis occur? Is this more or less common than Chorionic Villus Sampling?

A

When the fetus is 14-16 weeks. This is more common, because people generally know they are pregnant by then.

43
Q

At what stage of development does Chorionic Villus Sampling occur? Is this more or less common than Amniocentesis?

A

This is earlier in development when the fetus is 8-10 weeks. This is less common, because women may not be sure that they are pregnant by then.

44
Q

How many mendelian (single gene) diseases are there? Are these rare or common?

A

There are about ~4000 of these and they are rare genetic diseases.

45
Q

Describe Mendelian Diseases.

A

It is easy to find the disease genes (most have already been found).
However, they can have incomplete penetrance.
The severity of them varies based on genetic background, epigenetics, and environmental factors.

46
Q

By far, what are the most common genetic diseases?

A

Multifactorial and polygenic (multi-gene) disorders.

47
Q

Describe Multifactorial and Polygenic Disorders.

A

It is difficult to find the disease genes.
Environment (environmental triggers) and Epigenetics (stochastic or affected by environment) affect the severity of the disorder.

48
Q

Name the 3 common molecular markers.

A

Restriction fragment length polymorphism (RFLP)
Amplified Restriction Fragment Length Polymorphism (AFLP)
Microsatellite (a.k.a. Simple Sequence Repeats and Short Tandem Repeats)

49
Q

What is a Restriction fragment length polymorphism (RFLP)?

A

A region of a chromosome where the distance between two restriction enzyme cleavage sites varies among individuals.

50
Q

What is a Amplified Restriction Fragment Length Polymorphism (AFLP)?

A

A PCR fragment varies in size among individuals.

51
Q

What are Microsatellite (a.k.a. Simple Sequence Repeats and Short Tandem Repeats)?

A

A site in the genome that contains short sequences that are tandem repeats and are unstable. The total length is usually in the range of 5 - 200 bp. Length determined by PCR.

52
Q

Describe the process of identifying a microsatellite polymorphism.

A

1) Add PCR primers to a set of chromosomes.
2) PCR primers will flank tandem repeats on a particular microsatellite.
3) Run a PCR on gel

53
Q

Why are there different sizes of microsatellite fragments on the gel?

A

Different sizes is due to low instability which can impact size

54
Q

What does gel of PCR products for a polymorphic microsatellite allow for?

A

Allows us to see if a child has a disease inherited from parents by comparing the parents and child’s matching size fragments.

Alex's Genetics (38 decks)

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