BIOL 104 test 1

First test 9/14 MON night biology... I shouldve started this last night....

theory

bringing together multiple hypothesis through an explanation and lots of evidence

population

individuals of the same species

communities

collection of populations in the same area

ecosystems

communities PLUS abiotic factors (water, temp, sunlight)

Biomes

collection of very similar ecosystems, largely bound by global influences like weather and climate

Biosphere

all biomes put together (climate change n other global issues)

emergent property

traits/abilities that emerge when individuals interact with eachother. whole is greater than the sum of its parts.

Lamarck

first one to come up with acquired characteristics (giraffe neck example)

evolution

change in genetic (allelic) frequency within a population over time

Natural selection requires

variation, heritability, diffrential survival, diffrential reproduction

adapation

heritable trait that increases the fitness of the individuals who have that trait AND the process

evidence for evolution

species are related, they change over time, and evolution can be seen in the short term (over generations, MICRO)

vestigial trait

commonly found in a species that no longer serves a function

atavism

a vestigial trait found in few individuals in a species

contrivance

adaptation as a result of a modification of the original trait

exaptation

it was adaptive before, but now provides the new initistal stage to become a contrivance.

homology

similiarity in traits as a result of a common ancestor

homoplasy

individuals with common traits WITHOUT COMMON ACNESTOR

phenotype

measureable traits, caused by genotypes

white, grey, black,

genotypes

causes phenotypes, codes for traits

Bb, BB, bb,

genome

all hereditary information in an individual

gene pool

all alleles of the genes within a population.

alleles

versions of a gene that occur at the same locus on homologous chromosomes

genotype can result in diff phenotypes bc…

environmental pressures. (Some identical twins can be not the same)

definition of a “set” of chromosomes

how much u get from a parent: humans have 23 chromosomes in each set

ploidy

number of chromosomes in a set and the number of sets of chromosomes a cell contains

homologous pairs of chromosomes

one copy of same chromosome from each parent (same genes)

meiosis

halfing the number of chromosomes and creating SPERM and EGG gametes.

Why does meiosis have I and II?

to increase variation

sister chromatids

identical, from the same parent

First area of variation MEIOSIS

non-sister chromatids create Chiasma, and CROSSOVER

Second area of variation MEIOSIS 1

tetrads line up, RANDOM ASSORTMENT in meiosis 1 (can randomize between father and mother)

Third area of variation in Meiosis (II)

again, random assortment when lining up to form final gametes, MEIOSIS 2

How much variation without crossing over?

2 homologous pairs makes 4 gametes, so 2ⁿ where n=haploid number of chromosomes

how much variation WITH crossing over?

occurs randomly, so INFINITE

aneuploidy

happens in 10% of meiotic divisions, most not expressed though

INCORRECT # OF CHROMOSOMES

nondisjunction

during meiosis I and 2, one cell ends up with both pairs of homologs of one chromosome

trisomy

texample: down syndrome, 3 copies of chromosome at chromosome 21.

unequal crossing over as variation:

one arm of a chromatid ends up longer than its sister (huntingtons disease)

causes of mutation

radiation, chemicals, physical irritation,

transformation (variation in asexuals)

bacterial cells take up DNA fragments from other cells and either incorporate to its own DNA or leave it as a separate plasmid that can replicate by itself.

Transduction (variation in asexuals)

viral capsids attatch to bacterial cells and inject their DNA

conjugation (variation in asexual)

a tube transmits plasmid to a cell without plasmid… sometimes only a fragment is given which allows for a new variant

mendel

filling the gaps of darwin: how traits are inheritded

looking into why offspring often not a blend of parents

mendel law of segregation

allele pairs separate to form gametes

Mendels Independent assortment

one allele of a trait has no effect on the probability of another trait (true, but only on traits on different chromosomes)

test cross

to find out if an organism is homo dominant or hetero, they cross it with a recessive and see offspring .

Reciprocal Cross

Crossing the opposite way: MORGAN and found out about sex-linked

autosomal inheritance

inheritance of genes located on NON sex chromosomes

multiple allelism

The occurrence of more than two alleles for a locus in a population, even though only one occurs on each chromosome

Human blood types

iA, iB, I…. 3 alleles

(remember only 2 alleles per locus at a time can occur in a cell.

Beta-globin gene

making hemoglobin has over 500 different alleles that affect loads of variations having to do with living at various altitudes, different temperatures and resisting diseases.

incomplete dominance

when heterozygous can show a MIX of phenotypes (red and white make PINK)

codominance

heterozygous can have two distinct phenotypes (brown spots on a cow)

polygenic effects

single trait is affected by many genes, ADDITIVE (like skin color)

pleiotropic effects

one gene has many characteristics

one allele has many traits

epigenetic effects

environment can turn on and off certain genes, and this can last for generations and be turned on and off still.

autosomal dominant

appears in EVERY GENERATION

everyone affected has an afffected parent

autosomal recessive

often skips generations, unaffected parents (carriers) can have an affected child