Genomes

Question 1

why are genomes different sizes in diff organisms

Answer 1

lol we dont know it’s just how it is,
C paradox

Question 2

how much % of our DNA encodes for proteins

Answer 2

3%
~20,000 genes

Question 3

how much % are regulatory genes

Answer 3

10%

Question 4

how much is junk in our genome %

Answer 4

~85%
45% is repetitive elements

Question 5

what did Barbara McClintock suggest

Answer 5

that genes can move about on chromosome
won nobel prize for it

Question 6

what’s the name for mobile genetic elements

Answer 6

transposons

Question 7

what do transposons do

Answer 7

sequences of DNA that can move in the genome
some produce transposase
= enables ‘ungluing’ at either end and can ‘jump’ to where it wants

Question 8

what is retrotransposons

Answer 8

produce RNA which is reverse transcribed into the genome
they kinda insert themselves somewhere else

remnant of retroviruses

Question 9

what can movement of a transposon cause

Answer 9

produce mutations
can be involved in cancers, developmental disorders etc.

Question 9

how can transposons prevent their own transposition

Answer 9

produce small interfering RNA

Question 10

see one note for fish example on translocation

Answer 10

:)

Question 11

how have retroviruses lead to the us bein gbal eot make placenta

Answer 11

genes that once encoded for the envelope of the retrovirus
was harnessed
now used to make syncitins
which is a protein needed to make placenta

Question 12

how did cows get 25% of their genome frmo snakes

Answer 12

ticks
sucked blood from snake
one day the tick bit the ancestor of the cow
then it goes into bloodstream
eventually finds its way into the sex cells
is passed down

Question 13

example of horizontal gene transfer in humans

Answer 13

mitochondiral DNA integrated into our nulcear DNA

Question 14

what is typically needed for horizontal gene transfer in multicellular organisms

Answer 14

an intermediate
ie a parasite or some kind of symbiote

Question 15

example of horizontal gene transfer that led to red colouration in pea aphids

Answer 15

usually green but some are red
the gene to turn red acquired from fungus

Question 16

what are some examples of genes taht are necassary to be an animal

Answer 16

homeobox developmental genes
cell adhesion molecules
receptors

Question 17

what is environmental DNA

Answer 17

exctraction of sequences without the organism
mainly from soil, water, air etc

non invasive observational technique

Question 18

when can eDNA be useful

Answer 18

to identify kinds of organisms down in deep ocean from bits of DNA collected

Question 19

why is collecting eDNA difficult

Answer 19

needs careful amplication and bioinformatic identification

cuz could easily be contaminated

Question 20

on average, how much do humans differ to each other by

Answer 20

0.1% (only about 3 million base pairs)

Question 21

why was human genetic variation initially underestimated

Answer 21

cuz all samples were european volunteers

Question 22

what part of the world has the most genetic variation in humans

Answer 22

those with african descent
have ~10% more DNA than the ‘reference’ DNA (from the european sample)

Question 23

example of humans still evolving: tibetans

Answer 23

study comparing tibetans (who’ve lived at high altitude for longggg time) and han chinese (who are migrants so only recently moved)

showed the tibetans more liekly to have EPAS1 gene
controls RBC production so better at high alt
only 9% on han chinese had it

Question 24

example of humans still evolving: bajau people

Answer 24

they dive for long periods of time to fish

they have much bigger spleens that acts as a resovoir of RBCs
and another gene that lets them hold breath for longer

Question 25

evidence of an ancient coronavirus?

Answer 25

studied DNA of genes for proteins that interact with coronaviruses in indegenous people (cuz they have less mixing of genes and stuff)

strong sign of selection for a gene that prevents or promotes replication in the lungs from around 20,000 yrs ago

obvs those that could prevent survived and that gene is seen in populations today

Question 26

how might dark and light skin vary in different environments

Answer 26

dark skin protects from UV

lighter skin enable vit D biosynthesis wherever the sun is weaker

Question 27

~how many genes involved in skin colouation

Answer 27

at least 15 genes hence the amount of variability in skin colours