Chromosomes,Alleles, Loci Powerpoint slides

Question 1

What is a gamete (as opposed to a somatic cell?)
Select all that apply

reproductive cells
sex cells
egg
sperm
muscle cells
skin cells
blood cells

Answer 1

reproductive cells, sex cells, egg, and sperm

Think of gametes are meant for two eggs and sperm :)

Question 2

Egg and sperm are what?

Answer 2

Gametes

Question 3

What is a somatic cell?

Select all that apply

reproductive cells
sex cells
egg
sperm
muscle cells
skin cells
blood cells

Answer 3

muscle cells, skin cells, blood cells

Question 4

Diploid means

Answer 4

each chromosome has a pair

Question 5

How many chromosomes do diploid cells have?

Answer 5

46 chromosomes

Math calculation (23x2)=46 chromsomes

Question 6

Haploid meaning

Answer 6

there is 1 of each chromosome

Question 7

How many chromosomes does a haploid cell have?

Answer 7

23

Question 8

_____________refers to any of non-sex chromosome located in the nucleus

(This flashcard is for my own knowledge not from lecture notes)

Answer 8

Autosome

Question 9

Pairs of autosomes are ______________

Answer 9

homologs

Question 10

X and Y chromsomes are NOT homologs

Answer 10

True

Question 11

_______-location of a gene in the genome

Answer 11

locus

Question 12

______-variant of gene sequence

Answer 12

allele

Question 13

Normal somatic cells carry two alleles for each locus

Answer 13

True

Question 14

Another way to say Diploid is _____

Answer 14

2N

Question 15

Another way to say haploid is ____

Answer 15

1N

Question 16

_________ is fusion of two gametes (egg and sperm)

Answer 16

Zygote

Question 17

Gametes must have mitochondria the egg is has mitochondria

Question 18

What is the difference between a gamete and a zygote
A.Gametes are 1N, Zygotes are 2N

B.Gametes do not have a mitochondria, zygotes do

C.Gametes are diploid, Zygotes are haploid

Answer 18

A. Gametes are 1N, Zygotes are 2N

Question 19

the process of cell division that occurs to produce gametes

Answer 19

Meiosis

Question 20

____________-interphase incorporates s phase, after s phase DNA would be replicated, sister chromatids would be formed..then diff. phases like prophase, metaphase,telophase, that results in cytokinesis which is 2 cells in the end have 2N they are diploid

Answer 20

Mitosis

Question 21

What kind of cells result from mitosis?

Answer 21

Somatic cells like skin cell or gut cells…start out as 2n go through cell cycle throughout process of cell cycle that dna gets replicated to be formed and they divide and end up as 2 2N cells instead of 1 2N cells

Question 22

Which of the following would result in an individual
having a disorder? (Select all that apply)
1. Someone who is heterozygous for a dominant disease mutation.
2. Someone who is homozygous for a dominant disease mutation.
3. Someone who is heterozygous for a recessive
disease mutation.
4. Someone who is heterozygous, but carries two different recessive disease mutations.

Question 23

At the end of mitosis what is produced?

Answer 23

Two diploid cells which are identical

Question 24

At the end of meiosis what is produced?

Answer 24

four haploid cells at the end of meiosis II

Question 25

Homologous Recombination

Occurs during ___________________
of meiosis
* Results in increased
genetic variability

Answer 25

Prophase I

Question 26

Which of the following can result
in genetic mutations?
1. Mistakes by DNA polymerase
2. Damage of DNA bases by ROS
3. Breaks to DNA backbone by ionizing radiation
4. All answers are correct

Question 27

Types of Genetic Variants/Mutations
Point mutations—>could be inconsequential
* Insertions (repeat expansion)–>serious
* Frameshifts–>serious
* Deletions–>serious
* Structural changes–>serious
* DNA breaks–>serious
* Addition or deletions of whole chromosomes–>serious
* Chromosomal–>serious

Question 28

is defined as having the same sequence in
both alleles (both chromosomes) at a particular locus

Answer 28

Homozygous

Question 29

____________ is defined as having differing sequences in both alleles

Answer 29

Heterozygous

Question 30

Gregor Mendel’s Experiments
* Effects of one allele at a particular locus can mask the
effects of a different allele at the same locus
– Dominant versus recessive

Question 31

Homozygous for short allele (hh) X Homozygous for tall allele (HH)= Heterozygous (Hh)

Question 32

Both mutations and polymorphism are changes in the DNA sequence

Question 33

Mutations are very _______

Answer 33

rare

Question 34

_____________ are loci in the genome that
commonly have varied sequence in the population,
where the least common sequence is still in at least
1% of the population
– Single nucleotide polymorphism = SNP

Answer 34

Polymorphism

Question 35

~0.00025% incidence of Factor 8 mutation in males causing hemophilia A

Is a mutation or polymorphism?

Answer 35

(THIS IS A MUTATION!…WAY LESS THAN 1%..generally mutations are selected against we don’t select for these mutations usually that’s why they have very low incidence in the population

Question 36

40% incidence of A allele for glycosyltransferase resulting in A blood type in US

Is this a mutation or polymorphism?

Answer 36

This is a polymorphism because its more than 1% and there’s really no selection for or against this…it doesn’t really have any necessary benefits or opposite that’s why there its kind of sort kind of there certain amount in a population and different population might have slightly different change but its not really being selected for or against

Question 37

Why would fewer percent of the population carry a sequence change causing disease? Is this a mutation or a polymorphism?

Answer 37

selected against…it’s either they are not going to be able to pass on their genome because they are sterile or its selected for and doesn’t really have a negative effect then it may result in more of the population having that genetic variant and so it becomes a polymorphism

If you look at whole species any variation in the genome starts off in one person initially they inherited some genetic change from their parent that was a random mutation that occurred in the gamete that produced them and the question is whether that selected for or against or doesn’t even matter…do they pass it off to their offspring and it always starts out that less than 1%

Question 38

Could a mutation in one population be a polymorphism in another?

Answer 38

YES! It really depends on what population your looking at and what environment there in and whether there is selection for or against that genetic variant

Question 39

______________->switching from a serine to an asparagine (so a change in the amino acid sequence at one amino acid

Answer 39

missense mutation

Question 40

____________->one nucleotide change; switching from a codon sequence for an amino acid to a codon sequencing for a stop codon ..so that means that amino acid will NOT be incorporated nor any other of the amino acids that were coded for afterwards

Answer 40

nonsense mutation

Question 41

Splicing is important because there are certain sequences that are telling where splicing should occur…if those sequences somehow get changed then splicing will NOT occur properly
Ex: GT…that this GU that’s important for splicing of this intron and exon…splicing these two exons together if that GT got mutated to an AT now the spliceosome is going to skip pass this because it doesn’t recognize that as a splice site anymore and it will go downstream to the next GT and it will splice there instead. Now you have all this intron that’s contained within the final mRNA that shouldn’t have been…because it doesn’t splice where it would have normally because that splice site got mutated

Question 42

You could incorporate or add an additional splice site…so it might splice further up or further down or not splice at all depending on how those sequences get mutated

Question 43

Insertions and deletions
(Can insert or delete whole codons or whole amino acids from a portion of a protein so it means that there is chunk that either comes out or is added in but everything else besides that is the same so those are just typical insertions or deletions but if that insertion or deletion is NOT a divisible by 3 then it will result in a frameshift that means anywhere after that insertion or deletion everything after that is messed up

Question 44

Often times during with a frameshift not only is it that every amino acid are not the normal sequence but it also incorporates a stop codon…not only will be an abnormal sequence but it will have a shorten sequence as well…why is this harmful? That protein is not going to work well or at all as opposed to a missense where a majority of the protein is okay so there’s diff. levels of affect on the phenotype

Question 45

__________- are SNPs that result in a
change of one amino acid in the resulting
polypeptide sequence

Answer 45

Missense mutations

Question 46

___________ are SNPs that result in the
introduction of a stop codon in the mRNA
sequence causing inappropriate termination of
translation and a truncated protein product

Answer 46

Nonsense mutation

Question 47

If a point mutation alters the sequences within
introns that are required for splicing this could (b)
block the normal splicing that occurs, or (c)
introduce new splice sites, resulting in an altered
mRNA sequence and translated protein.

Question 48

Insertions and deletions of base pairs can result in added or deleted AAs or alter the reading frame of the mRNA (frameshift mutation)

Question 49

Frameshift mutations are
especially harmful

Question 50

____________ mutations ->
Result in dominant disorders.

Answer 50

Gain of function

Question 51

______________ mutations ->
If 50% of normal protein is
adequate then no disease, if
haploinsufficient (50% of protein
is not adequate) results in
dominant disorders.

Answer 51

Loss of function

Question 52

______________ mutations ->
Generally causes problems with
proteins forming multimers

Answer 52

Dominant negative

Question 53

____________->there is one normal allele and one mutant allele…this mutant allele produces novel meaning something is different about this protein somehow or there is more of that protein and so because of this whatever the change in this is or whatever the excess of this is it results in a dominant disorder so its gaining some function and it will cause the disease even though its heterozygous

Answer 53

Gain of function

Question 54

___________ mutations—>you have a normal protein on one allele but with this loss of function the protein is not expressed at all anymore or the protein is not functional anymore its loss of function so you lack the function that you would normal have from this second allele…this one it depends whether it causes the disease or not in a heterozygous scenario…if 50% of normal protein is adequate then they won’t have the disease…if 50% of the protein is not adequate which is defined as haploinsufficient that will result in a dominant disorder..if its sufficient recessive… if is halpoinsuffienct its dominant

Answer 54

Loss of function

Question 55

___________ mutations because this one allele is somehow disrupting the function of the protein that’s expressed from the normal allele or wild type…usually in proteins that form multimers or complexes so basically you have the screwed up protein here and normal protein here…this normal protein isn’t able to function because its binding with some complex with the screwed up one and its disrupting the whole function all together so it’s a dominant disease

Answer 55

Dominant negative

Question 56

If you a scenario where there is 50% of normal function…this isn’t a heterozygous scenario so they have 50% of normal function because they 1 normal allele…if 50% of normal function is not sufficient to function normally overall then they will have the disease so whatever this protein is suppose to do the amount of protein that’s produced from this one allele is not sufficient to do whats its suppose to do in that cell so there will be a disease

Question 57

If they are heterozygous and have 1 mutant allele for a gain of function mutation, will they have the disease?

Answer 57

YES!

Question 58

If they are homozygous and have 2 mutant alleles for a gain of function mutation, will they have the disease? __________

Answer 58

YES!

Question 59

If they have a haplosufficient loss of function mutation and they have 1 mutant allele, will they have the disease? _____ BECAUSE ITS HAPLOSUFFICIENT IF IT WAS HAPLOINSUFFICIENT meaning expression from one normal allele was NOT sufficient to have whatever normal function they needed in that cell then they would have the disease

Answer 59

NO!

Question 60

If they have a haplosufficient loss of function mutation and they have 2 mutant alleles, will they have the disease?

Answer 60

YES!

Question 61

For a dominant negative mutation, if someone has 1 mutant allele, will they have the disease?

Answer 61

Yes! Because that mutation disrupts the normal allele

Question 62

If they are homozygous,meaning they have 2 mutant alleles,will they have the disease?

Answer 62

YES

Question 63

If it was haploinsufficient loss of function now they are heterozygous they only have 1 mutant allele they have one normal and one mutant is that one normal enough to prevent them from having the disease?

Answer 63

No they will have the disease…if they are homozygous they will still have the disease

Question 64

True homozygote have the same mutation on both alleles…same variation lets say Patient A is homozygous for a loss of function mutation

Question 65

Compound heterozygote–>have mutations on both alleles but they are not the same mutation so they are heterozygous because the sequence on that locus is NOT identical but they still have mutations on both alleles

Question 66

If its loss of function and recessive does that mean its haplosufficient or haploinsufficient? Haplosufficient

Question 67

Would patient A develop the disease? YES! Its recessive because its haplosufficient but they are homozygous for that allele so they are going to get the disease

Question 68

Patient B is still loss of function mutation and its recessive so it means these mutations are both loss of function and they are both haplosufficient but each chromosome has a loss of function mutation so would patient B get the disease? YES!

Question 69

Why is loss of function in a haplosufficient scenario lets say its heterozygous one allele would have the normal expression you have something from that allele that has function and if its haplosufficient that means its sufficient to have normal function so even if you lose the other allele you don’t have the disease but professor stated you don’t have that normal allele… both alleles are loss of function its 2 different mutations that are causing that loss of function but its still loss of function so patient B would still have the disease

Question 70

Loss of function you normally have 2 chromosomes, 2 functioning genes, if you lose one of them its haplosufficient its recessive that’s okay but you lose the other one it doesn’t matter how you lost that other one if they are both loss of function your going to have the disease you need something…you need that protein that’s produced from that gene that’s connecting the genotype to the phenotype

Question 71

Why does a genotype cause the phenotype of the disease? Because on a molecular level something is happening that gene…that protein is produced from that gene is different somehow…its different structurally just not there

Question 72

Could patient A and patient B present differently? YES! Maybe a person might have a less drastic case of the disease or drastic phenotype versus this one or vice versa

Question 73

How much of a loss function could be different if its diff. mutations so loss of function doesn’t say 100% loss of function its just loss of function…maybe the protein structure isn’t quite right…so it doesn’t do its job quite as normal or maybe its just gone completely which is just a worser effect

Question 74

Penetrance=if somebody has the mutation and they should have the disease based on pure genetics based on evidenced we know that this is a dominant disorder they have the mutation they should ave the disease but not everybody always does…there is this term called penetrance is it 100% penetrance…historically if we study people who have this mutation 100% of the time they get the disease sometimes its 90% of the time or 80% of the time so there’s different kind of effects on penetrance

Question 75

Penetrance means if you have the mutation will you have the phenoytype so potentially this could effect penetrance if you have a diff. mutation its not the identical same mutation so the penetrance maybe a little bit different

Question 76

Sickle Cell Disease
Missesense mutation (GLU to VAL) ; Caused by a change in a single amino acid due to a point mutation in the beta subunit of hemoglobin;Disc shape with a little indented centernormal red blood cell; Sickle cell catch in the vascular, they don’t carry oxygen properly
-Results in sickling and destruction of RBCs
-Affects 70,000 people in the US primarily those with African, Mediterranean, Indian, or Middle Eastern ancestors
-1/600 in African Americans, 1/50 in certain African populations
-Mutation or polymorphism?
Mutation and polymorphism is really about what population are you looking at so if we look in African americans for sickle cell disease the incidence is 1/600
Which population is it a polymorphism in? certain African population (1/50) because 1/50 its more than 1%

(Mutation is less than 1%)
(Polymorphism is more than 1%)
(Its all about the population your talking about;same exact mutation; same exact genetic change can be mutation in one population ex: 1/600 or polymorphism in another population)

Question 77

When thinking in terms of evolution; what if there is a negative effect due to a mutation? It is selected against and not passed down; those genes are not passed which make sense in some population its less common its more rare to be of a mutation

Question 78

Since there is a benefit (being less likely to get malaria) associated with being a carrier, what do you think will happen in terms of evolution for those specific populations? It is selected for and passed down; its favorable to be a carrier of this mutation in a location that you may be exposed to malaria

There is selection for being heterozygous but if two heterozygous people mate then there offspring could have the actual disease because they could become homozygous for