BIO EXAM 3

Question 1

What is genetic drift?

Answer 1

Random changes in allele frequencies; most important in small populations

Tends to reduce genetic variation via loss or fixation of alleles

Usually reduce avg fitness

Question 2

S3 Figure Results

Answer 2

The rapid decrease in the frequency of cooperative E. coli represents the point at which methionine became abundant enough that the costs of galactose excretion outweighed the benefits of increased access to the amino acid

Question 3

What is inbreeding depression?

Answer 3

The decline in average fitness that may
take place when homozygosity increases and heterozygosity
decreases in a population

• Many recessive alleles represent loss-of-function mutations
• Many disease-fighting genes are under intense natural selection for heterozygote advantage,
  a selection process that favors genetic diversity

Nonrandom Mating + Natural Selection = Evolution

Question 4

What is “Species” ?

Answer 4

A group of organisms made up by related individuals able to produce fertile offsprings

Question 5

What is a phylogenetic tree?

Answer 5

Visualization of phylogeny of the evolutionary history among groups of organisms

1. We are more phylogenetically similar to yeasts than yeasts are to bacteria.
2. Only 10,000 species found and named in the world
   3.1,000 species in your gut; a teaspoon of soil contains 1 billion bacterial cells.

Question 6

What is a phototroph?

Answer 6

An organism that can use visible light as a primary energy source for metabolism

Question 7

What is sympatric speciation?

Answer 7

Speciation that happens to individuals in the same geographic area.

DNA sep. from apple maggot flies & Hawthorn maggot flies are similar, may have common ancestral being??

Question 8

What is vicariance?

Answer 8

Splitting of natural habitats to produce physical barriers. Ex: 8 species of trumpeter birds from amazon forest

Question 9

What is an auxotroph & heterotrophs

Answer 9

A: (“self-feeders”) synthesize their own com- pounds from simple starting materials such as CO2 and CH4.

H: (“other-feeders”) absorb ready-to-use organic
compounds—called building-block compounds—produced by other organisms in their environment.

Question 10

What is homology?

Answer 10

Traits that are shared among individuals with the same ancestor

Question 11

What are prokaryotes?

Answer 11

Bacteria & Archaea

1. Are unicellular
2. Lack a membrane-bound nucleus
   (unlike eukaryotes)
3. Lack organelles (unlike eukaryotes)

Prokaryotic cells are usually 10 times smaller than eukaryotic cells!

Question 12

What is homoplasy?

Answer 12

Traits that are shared among individuals who do not have a close common ancestor

Question 13

What are eukaryotes?

Answer 13

Non-prokaryotes: animals, fungi, plants etc

1. Have DNA wrapped in a
   chromosome in a membrane-
   bound nucleus

Question 14

What is tuberculosis?

Answer 14

TB is caused by bacteria (Mycobacterium tuberculosis) and it most often affects the lungs.

Question 15

What is Penicillium?

Answer 15

Is a type of mold, colors like green and blue

It’s found in soil, decaying matter, and food

Some types are useful for making cheese and antibiotics, but others can spoil food or cause health issues

Question 16

What is metabolism?

Answer 16

All chemical reactions in an organism.
Purpose: Sustain life by converting food to energy, building cells, and eliminating waste.
Categories: Anabolism (building molecules) and catabolism (breaking down molecules).

Question 17

What is an allele?

Answer 17

Allele is a variation/alternative form of a gene.

Question 18

What is a gene?

Answer 18

A gene is a unit of DNA sequence that is responsible for encoding a biological function.

Question 19

Differences between Gene & Allele

Answer 19

A gene describes the heritable element for a biological function, whereas an allele is an alternative form
of a gene.

Question 20

What is gene linkage?

Answer 20

Some genes get passaged to offsprings together, which means that in a chromosome, two genes occupy close-by loci and therefore move together to the
offspring.

Question 21

Mutation

Answer 21

Mutations happen when DNA polymerase makes errors in DNA replication (10-9,10).

Question 22

Types of Mutation

Answer 22

1. Point mutations: a change in a single nucleotide in DNA.
2. Chromosome-level mutation: A change in the number or composition of chromosomes.
3. Lateral gene transfer (horizontal gene transfer): Transfer of genes from one species to
   another.

Question 23

Mutation is what ?

Answer 23

Is the ultimate source of genetic variation.

Question 24

If Mutations were to stop occurring

Answer 24

Evolution would eventually stop (Biological innovation).

Question 25

What is gene flow ?

Answer 25

Movenment of alleles between populations; reduces differences between populations May increase & decrease generate variation by either introducing or removing alleles May increase or decrease average fitness

Question 26

Nonrandom Mating..

Answer 26

Heterozygous: Having two different alleles for the same gene (locus) (e.g. Bb). Homozygous: Having two identical alleles for the same gene (locus) (e.g. BB, bb). Inbreeding: Mating among relatives (Plants self-fertilize)

Question 27

What are the key consequences of genetic drift?

Answer 27

1. Genetic drift is random with respect to fitness. 2. Genetic drift is most pronounced in small populations. 3. Over time, genetic drift can lead to the random loss or fixation of alleles.

Question 28

What causes genetic drift ?

Answer 28

1. Founder effects: A change in allele frequency that occurs when a new population is established (migration) 2. Genetic bottleneck: A sudden reduction in the diversity of alleles in a population (e.g. volcanic eruption, other catastrophes).

Question 29

What is Antibiotic Resistance ?

Answer 29

The ability of bacteria to grow in the presence of an antibiotic

Question 30

What is Speciation ?

Answer 30

A spitting event that produces 2 or more distinct species from an ancestral species, so they become REPRODUCTIVELY ISOLTAED

Question 31

Pre-Zygotic Isolation (1 types of reproductive isolation)

Answer 31

1. Pre-zygotic isolation prevents individuals of different species from mating successfully EXAMPLE: Mechanical, dogs, incompatibility

Question 32

Post-zygotic isolation (2nd type of reproductive isolation)

Answer 32

2. Post zygotic isolation: prevents hybrid offsprings from surviving or reproducing properly. EXAMPLE: Hybrid sterility, horse & donkeys, their hybrid unable to reproduce

Question 33

How does speciation happen?

Answer 33

1. Allopatry (different homeland): genetic isolation between pop. that occurs because they're geographically separated 2. Sympatry (same-homeland): speciation occurs even though pop. live in the same area

Question 34

Allopatric Speciation by Dispersal

Answer 34

1. Geographic Isolation: Some individuals disperse from their pop. & colonize a new habitat 2. Divergence: New pop. begins to diverge due to mutation, genetic drift, and selection 3. Genetic Isolation: Eventually the two pops. are genetically isolated from one another

Question 35

Allopatric Speciation by Vicariance

Answer 35

1. Geographic isolation: chance event physically separates pops into subgroups 2. Divergance: isolated populations begin to diverge due to mutation, genetic drift, and selection 3. Genetic isolation: Eventually the two pops. are genetically isolated from one another

Question 36

What is Phylogeny ?

Answer 36

Evolutionary history/relationship among species, pops., or other groups.

Question 37

What is Polygamy ?

Answer 37

A node that depicts a branch dividing into 3 or more descended branches

Question 38

How are phylogenetic tress built up?

Answer 38

1. use DNA information or morphology info 2. Group based on shared traits 3. Identify a root

Question 39

Adaptive Radiation

Answer 39

Occurs when a single lineage rapidly produces many descendents with a wide range of adaptive forms Ex: Cacti

Question 40

Medical Significance of Prokaryotes

Answer 40

1. Bad: Infectious disease - Invade tissues of host organism (TB) - Producing toxins 2. Supporting health - Produce essential nutrients -Digest Food - Maintain host Health

Question 41

Environmental significance of Prokaryotes

Answer 41

1. Nutrient recycling - Decomposers - Denitrification 2. Bioremediation - Degradation of toxic chemicals humans produce (oil spill) 3. Agricultural fertilizer - Nodule formation with legume plants

Question 42

How to Study Microorganisms?

Answer 42

- Metagenomic approaches - Enrichment culture

Question 43

Metagenomic approaches

Answer 43

- Using DNA information from the entirety of environmental/host- associated samples to predict the microbial members in each sample. - Provide information on identity of microbes in a sample.

Question 44

Enrichment culture

Answer 44

- Bacteria are rich in numbers and invisible to see. - In an enrichment culture, we establish a specified set of growing conditions— temperature, lighting, substrate, types of available food, and so on—for a specific type of bacteria to grow in numbers to be isolated and studied in detail.

Question 45

Isolation + Enrichment

Answer 45

Repeating streaking over and over on different agar leads to isolated strain.

Question 46

Microbiome

Answer 46

Community of microbes that naturally inhabit the body.

Question 47

Lateral gene transfer:

Answer 47

Transfer of genetic material between across mating barriers (usually in less related organisms). Common approaches: -Transformation -Conjugation -Transduction

Question 48

Transformation

Answer 48

Prokaryotes take up DNA in the environment that has been released from cell lysis or secretion.

Question 49

Conjugation

Answer 49

-Transferring genetic information by direct cell-to-cell contact. -Aka bacterial “sex.”

Question 50

Transduction

Answer 50

- Bacterial viruses infect the prokaryotic cell and transfers its DNA to another cell.

Question 51

A consequence of gene transfer

Answer 51

- Spread of antibiotic resistance genes

Question 52

Prokaryotes produce ATP in 3 ways

Answer 52

Phototrophs (“light-feeders”) use light energy to produce ATP Chemoorganotrophs (“chemical-carbon-feeders”) use organic molecules with high potential energy (e.g. sugars) to synthesize ATP Chemolithotrophs (“chemical-rock-feeders”) use inorganic molecules with high potential energy, such as ammonia (NH3) or hydrogen sulfide (H2S) to produce ATP.