Week 1

Question 1

Genetics

Answer 1

Is the study of genomic sequence variation

Question 2

Genomes

Answer 2

Are a set of instructions enclosed in a biological compartment

Question 3

DNA

Answer 3

A chemically inert molecule that stores information

Question 4

Central Dogma

Answer 4

gene -> transcript -> protein
proteins are associated with chemistry
RNA to some degree as well

Question 5

Allele

Answer 5

is a sequence variant

Question 6

How do alleles arise?

Answer 6

No genome is stable. changes occur all the time

replication mistakes;generation of alleles

In a growing population of genomes with no selection pressure,
The total number of alleles increase every generation.

Question 7

Genomes are not stable

Answer 7

Consequences:

The genome of the zygote accumulates alleles as it divides during development.

The fibroblast cells in your skin will have alleles not present in the zygote.

These new alleles can lead to cancer.

Question 8

There are no living fossils

Answer 8

Coelacanth first observed in the fossil record 390M years ago. Thought to be extinct for 66 M years. Caught in the 1938. They are lobed-limbed fish and cousins of us as tetrapods. Often called living fossils because of these “primitive features” but remember their genomes like ours has been changing over the past 390M years. They are not primitive.

Question 9

Genetics is the study of sequence variation. What does it tell us?

Answer 9

It can tell us about history of life and its evolution.

It can tell us about how inheritance works. Mendel and nuclear inheritance.

It can tell us about the chemistry of life. What genes are required for a process, like for instance circadian rhythm.

Question 10

Protein World

Answer 10

Can catalyze chemical reactions
Can potentially alter other proteins (e.g. prions)
‘Protocells‘ may have existed
concentrated proteins surrounded by lipid membranes.

Generally unstable
Function, but no heredity (can’t store genetic info)

Question 11

DNA World

Answer 11

Stores genetic information
Very stable
Without other
molecules…. boring

Question 12

RNA World

Answer 12

Can store genetic info
Can catalyze reactions: Ribozyme

RNA makes proteins
RNA makes more stable template of self in the form of DNA

Question 13

Three domains of life

Answer 13

Bacteria
Archae
Eukaryotes

they evolved from LUCA

a split occuring between bacteria, eukaryotes and archae followed by a second split between eukaryotes and archae

Question 14

Why do contemperary animal/protist genomes contain both bacterial and archaea genes?

Answer 14

1/3 of genes are of bacterial origin (alpha proteobacteria)

1/3 are of archaea origin

Last third of eukaryote genes arise from other bacteria or novel genes

Question 15

Origin of mitochondria is the origin of eukaryota

Answer 15

it has been suggested that archae and alpha-protobacteria got together in a genetic merge to give rise to eukaryote, they are a product of a genetic merger

Question 16

Steps for creating a eukaryote

Answer 16

1. Feeding
2. Endosymbiosis
3. Sharing
4. Entrapment
5. Transfer of control and genetic integration

Question 17

Endosymbiosis

Answer 17

2 distinct organisms

both free-living unicellular & both have a genome

Debate about when organism go from two to one organism:

1-Anaerobic archae
2-alpha proteobacterium aerobic

Scientists believe it’s a continuous process that there is no arbitrary line

Question 18

feeding

Answer 18

Feeding is not a common phenomenon, branches of archaea have the genetic and protein ability to feed

organism B undigested & inside A B hangs out inside A

Theres a benefit in this relationship, the bacteria provides more metabolites for the host cell

Question 19

Sharing

Answer 19

The host provides certain metabolites to the endosymbiont and vice versa the sharing is advantageous

but B can still survive outside A

They are still two distinct organisms involved in an endosymbitotic relationship

Question 20

entrapment

Answer 20

Genomes are not inherently stable, leading to a random mutation, a change in the genome of the host or the endosymbiont such that now the host or the endosymbiont is dependent for life on the other organism

endosymbiotic gene loss

B trapped inside A

Question 21

an evolutionary ratchet

Answer 21

A genetic change that increases the complexity of a biological system and that is hard to undo.

Question 22

an evolutionary ratchet

Answer 22

A genetic change that increases the complexity of a biological system and that is hard to undo.

Question 23

Entrapment

B trapped inside A: the relationship strengthens

Answer 23

Relationship stengths through other random mutations such that the host and endosymbiont are loosing genetic information such that they depend on one another more

Question 24

Gene transfer

Answer 24

from endosymbiont to host
Genes from the endosymbiont are transferred to the host.

Doing so results in the host gaining better control over the endosymbiont.

Question 25

How does horizontal gene transfer occur?

Answer 25

The gene is copied to the host chromosome from the endosymbiont, the gene exist in both genomes.

Subsequently the gene in the endosymbiont is lost.

Question 26

Experimental evidence of gene transfer.

Answer 26

Although this yeast cell has a TRP1 gene, it is in the mitochondrial genome and not expressed, because mitochondria do not have the ability to express nuclear genes.

The TRP1 locus in the nuclear genome is an inactive trp1 allele. Therefore, this yeast can not grow on medium lacking Tryptophan.

Plate the cells on a medium lacking Tryptophan

The TRP1+ locus has been transferred from the mitochondria to the nucleus and is now expressed and the cells can grow on a medium lacking Tryptophan.

Question 27

why aren’t all genes transfered?

Answer 27

These thirteen genes that produce proteins cannot be produce in the cytoplasm of the host it needs to be produced into in the organelle and then imbedded in the organelle membrane

Question 28

Consequence of the genetic merger:

Answer 28

Creation of the new domain Eukryota

When we created eukarotes we have an organism made up of two distinct membrane bound comaprtments

Feeding is the use of membranes to swallow food.

The production of energy of mitochondria is the main benefit for genetic merger, the extra energy allows the cell to engage in more complex arrangements of its genome.

All of the processes found in eukaryotic cells are genetically expensive.

Just the beginning of genetic mergeres

Question 29

origin of chloroplasts

Answer 29

The origin of mitochondria followed by other eukaryotic lineages entering into symbiotic relationship with cyanobacteria

Question 30

Secondary chloroplast

Answer 30

Non-photosynthetic eukaryote feeds on a eukaryote with a choloroplast

Secondary chloroplast surrounded by an extra member, the choloroplast has been fed on twice