Life Science Exam #3

mutations

changes in genetic information

where do mutations occur?

mitosis and meiosis

Can exposure to mutagens cause mutations

yes

point mutation

small changes in a sequence or number of nucleotides

substitution

one base is substituted for another

missence mutation

when a point mutation substitutes one amino acid for another

silent mutation

when a point mutation substitutes one base for another: does not result in a change of amino acids

nonsense mutation

when a point mutation substitution results in a premature STOP; resulting in protein often nonfunctional

Frameshift mutation

point mutation where bases are inserted or lost; the following code is thrown out of sequence

Chromosomal mutation

large scale changes in which all or part of the chromosome is changed

where do chromosomal mutations occur

occur during nuclear division

deletion

removes a chromosomal segment

duplication

repeats a chromosomal segment

inversion

reverses a segment with in a chromosome

translocation

moves one segment from one chromosome into a homologous chromosome

potential mutation results

both positive and negative, some mutations may have no effect

Transcription

production of a strand of RNA complementary to a strand of DNA

Translation

converts the information stored in RNA to a protein

What occurs after replication

each DNA double helix consists of one old strand and one new strand

What name is given to a trait (or collection of traits) you observe in an organism?

phenotype

What is the codon chart (blue chart from class)?

It is the genetic code representing the relationship between RNA and amino acids

How many amino acids are in living organisms?

20

Adeline pairs with

Thymine

Guanine pairs with

Cytosine

evolution

change in gene frequency in a population overtime

Mechanisms of Evolution

1. processes that produce genetic diversity

2. processes that change gene frequency

artificial selection (selective breeding)

-breeding things together to get the things we want

-goal oriented

-after organisms are domesticated-> often need humans

Natural Selection

-differential reproduction among members of a population due to environment

-some will produce more than others

-not a result of human intention

how does natural selection occur?

-members of the population differ genetically

-population members and the environment

-survival and reproductive success

what does natural selection result in?

change in gene frequency in population overtime

Types of natural selection include

1. directional selection

2. disruptive selection

3. stabilizing selection

4. sexual selection

Directional selection

-going in one direction

-everything in the environment in shifting in one direction

-selection for the one extreme

disruptive selection

-selection against the intermediate

-middle is selected against

stabilizing selection

-both sides are selected against

-selection for the intermediate

sexual selection

-traits that increase the likelihood of mating

-operates differently for males and females

-mate choice

-mate defense

intersexual

mate choice

females chose males

intrasexual

mate defense

Genetic drift

-changes do to chance

-founder effect

-bottleneck effect

bottleneck effect

large population that goes to a small population rapidly

minimum viable offspring

-smallest number a population we can have in a population that can survive without inbreeding

founder effect

genetic drift due to the establishment of a "new" population

Gene flow

changes due to immigration and emigration

immigration

entering a new population

emigration

leaving a population

Evolving population

-due to mutations and recombination genetic variation exists in the population

-due to natural selection some variants produce more offspring their genes will be more prevalent in the next generation

-genetic drift and gene flow also contribute

Non-evolving population

-no mutations

-random mating

-no selection

-extremely large pop. size

- no gene flow

Adaptations

an inherited trait that enhances an organism's ability to survive and reproduce in a specific environment

Microevolution

-small changes

-changes at or below the species level

-directly observable

Macroevolution

-large scale changes over long periods of time

-above the species level

-new species-> diversity of life on earth

-not directly observable

Descent with modification

-unity of life, we have a common ancestor

-diversity of life, modifications form ancestral organisms

Evidence of microevolution

-observable at human time scales

-hypothesis generation

-predictions

-testable

What is a species?

-group of organisms that can interbreed and produce viable, fertile offspring and cannot interbreed with other groups

mechanism for macroevolution

microevolution plus time

Evidence for macroevolution

specialization among reproductive isolated organisms

ex: animals on islands that are similar to the ones on the mainland but have different features.

Barrier to colonization

-genetic drift

-reproductive isolation

-disharmonic assemblages

-ecological opportunity

Hawaiian Chain

over 9000 species that are special just to the Hawaiian islands

Fossil record

-find earlier fossils further down the record

-gradual increase in complexity decrease with age

-environmental change -> organisms change

Homology

Same structures-> common ancestry

Different functions -> descent with modification

Analogous structures -> same function, different evolutionary origin

Development

-similarities in our development especially in the beginning

- show common ancsetory and then descent with modification

Molecular models

-some disagree with fossils

-some disagree with molecular evidence

biogeography

-some fossil evidence confusing

- some conflicts with molecular evidence

Buffon

proposed species can change over time

Lamarck

we will adapt to what we need, things we use we will grow with that trait

Darwin

evolution and natural selection

Lyell

proposed that things happen slowly in the form of uniformitarianism

RNA codes for

protein synthesis

Melonoma

-skin cancer

-increased UV light from the sun creates a somatic mutation and can effect certain cells under the skin

How many RNA bases code for one amino acid?

three

Where do large scale mutations occur

during cytokinesis

Pair bonding

those who are mated for life

Uracil

only in RNA

Inherited traits

adaptations