lec 16- The history in our genes

Question 1

MHC (major histocompatibility complex) genes have hundreds of alleles that control what?

Answer 1

immunity responses to antigens by linking T cells

Question 2

do most genes have more than 2 alternate alleles?

Answer 2

yes

Question 3

breast cancer gene (BRCA1) also has many alleles, how large is the gene?

Answer 3

120,000 base pairs

Question 4

what does BRCA1 normally act as and what happens when mutated?

Answer 4

acts as a tumor repressor, but when mutated it will increase breast cancer risk

Question 5

what is coalescence?

Answer 5

when alleles in a population can be traced back in time to a single common ancestor

Question 6

How was the breast cancer gene activated?

Answer 6

from one point mutation (G to T) many generations ago

Question 7

what thing do gene locations on chromosomes have?

Answer 7

their own genealogy (gene trees)

Question 8

is it possible to produce a consistent genealogy that agrees with a phylogenic tree based on morphilogical traits?

Answer 8

yes

Question 9

how do companies like 23andMe trace backwards to find out your ethnic backgrounds?

Answer 9

by tracing the history of many allele variants or mutations (called markers) to reconstruct the history

Question 10

what is very common in building a phylogeny with genetic data?

Answer 10

homoplasy because only four nucleotides to study in DNA sequences that make it common

Question 11

what are slowly evolving conserved genes useful for in the phylogeny?

Answer 11

distantly related species

Question 12

what are rapidly evolving genes useful for in the phylogeny?

Answer 12

closely related lineages

Question 13

who is mitochondria inherited from, and does the DNA undergo crossing over?

Answer 13

inherited from mother, DNA does not undergo crossing over

Question 14

what is the shape of the Mitochondria’s DNA?

Answer 14

a loop (like ancestral bacteria) that has 37 functional metabolic genes except in control region

Question 15

why is brown fat darker than normal fat?

Answer 15

because it is densely packed with mitochondria, which makes the fat warmer than normal due to respiration and high heat production

Question 16

is brown fat that is used in hibernation an ancient survival adaptation?

Answer 16

yes

Question 17

what are the four common methods in molecular phylogenetic analysis and tree building?

Answer 17

-Maximum Parsimony: simplest explanation favored
-Distance Matrix (neighbor joining): cluster taxa based on genetic distance (more different = more distant)
-Maximum Likelihood: finds most likely tree given specific model of molecular evolution
-Bayesian methods: looks at probability that a tree is correct given a specific model of molecular evolution

Question 18

what do humans have an identical Beta-globin protein with?

Answer 18

chimpanzees

Question 19

are phylogenetic trees hypotheses?

Answer 19

yes, they are constantly reevaluated when new data becomes available

Question 20

what are the two hypotheses behind human evolution?

Answer 20

-humans evolved from widespread species connected by gene flow and interbreeding
-humans evolved from a single African human ancestor

Question 21

who tested the blood DNA of modern africans to see if they had the highest genetic diversity (meaning it’s the origin of human evolution)?

Answer 21

Sarah Tishkoff

Question 22

which hypotheses of human evolution was supported?

Answer 22

-second, Africans displayed the most genetic variation (mutations) of mtDNA then rest of the world

Question 23

what is mtDNA (microsatellite DNA)?

Answer 23

non-coding repeating short sequences, high mutation rates

Question 24

did race evolve first in Africa?

Answer 24

no, physical characteristics like braincase, protruding chin and more evolved first in africa, while race evolved later

Question 25

where did neanderthals originate from?

Answer 25

eurasia

Question 26

when did neanderthals live?

Answer 26

in Europe and the near east from 200,000 to 28,000 years ago

Question 27

what were the characteristics of neanderthals?

Answer 27

stocky,strong, and thick boned with large brains (larger than modern humans)

Question 28

did neanderthals and humans interbreed?

Answer 28

yes

Question 29

what are the two main ideas behind the extinction of the neanderthals?

Answer 29

1. ice age, harsh temperatures and altered vegetation and animal distribution 2. competition from modern humans who left Africa around 60,000 years ago (most likely)

Question 30

what is HIV and AIDS?

Answer 30

-HIV: human immunodeficiency virus, two main types HIV-1 and HIV-2, with HIV-1 responsible for most infections in four main strains, both are retroviruses (RNA viruses) -AIDS: acquired immunodeficiency syndrome, is a medical condition that develops at the advanced stage of HIV infection, first diagnosed in 1981

Question 31

where did HIV-1 originate?

Answer 31

africa

Question 32

where did HIV-1 come from?

Answer 32

from chimps and gorillas that carry a similar virus known as the simian immunodeficiency virus (SIV), humans ate Bush Meat (chimps and gorillas) and SIV jumped to humans

Question 33

what are the four strains of the HIV-1 virus and where did they come from?

Answer 33

O and P- came from gorilla strains of SIV, and later transferred to chimps then humans M and N- evolved independently in humans, from two contact events with chimps