BIO114 EXAM 1

the two unifying themes in biology

1) cell theory 2) evolutionary theory

cell theory

all living organisms are made of cells, and all cells come from preexisting cells

evolutionary theory

species change over time. certain heritable traits allow for an individual to produce more offspring than other individuals within its population (and these traits will be seen more throughout).

biological hierarchy

A.O.C.T.O

atoms

organelles

cells

tissue

organisms

organismal biology

how the behavior and physiology of an individual contributes to reproductive survival and fitness

populations

a group of individuals of the same species living in a specific area and interacting with one another and their environment

community

different populations of different species (i.e. nature preserve, coral reefs)

ecosystem

a community + the abiotic factors

biosphere

the LIVING part of our planet, a compilation of all ecosystems

emergent property

a trait that exists at a particular level in the biological hierarchy that does not exist at the level below

an example of emergent property of the population level

sexual reproduction

Lamarckism

evolution by acquired characteristics (giraffes growing longer necks in their lifetime that will then be inherited by the offspring)

evolution

the change in allelic frequency in a population over time

natural selection

a process by which evolution can occur

4 components of natural selection

Variation, Heritability, differential Reproduction, differential Survival

homologies

structural, developmental, or molecular similarities between different species that are inherited from a common ancestor (i.e. bone structure of a human arm, a cat’s leg, and a dolphins flipper are all homologous structures bc they share a common underlying pattern inherited from a distant ancestor, even if they serve different functions today)

genetic homologies

similar gene sequences in different species that exist bc of a common ancestor (i.e. ancestors to the Galapagos mockingbirds had a slightly curved beak)

developmental homologies

homologies specifically during embryonic development (i.e. gill pouches in humans and house cats and chicks that come from our aquatic ancestors)

structural homologies

homologies but specifically to bone and skeletal structures that came from a common ancestor

adaptation

a heritable trait (phenotype) that will increase the fitness of an organism

contrivance

an adaptation within an organism that is different in the descendant compared to the ancestor

exaptation

the predecessor to a contrivance, it's the trait that an ancestor has which becomes a different trait over time in the descendant (the contrivance).

vestigial trait

a trait that everyone in the population has, which was an adaptation at some point in time (for the ancestors) but not in the present for the descendants

atavisim

a trait that relatively few members of the population have but all the ancestors likely had it.

homology

similarity in a trait between two individuals because they got that trait from a common ancestor

homoplasy

similarity in a trait between two individuals because they evolved them independently from one another

genome

all of the hereditary information within a cell, including nongenes (i.e. mitochondrial DNA, telomeres)

gene pool

all of the alleles of all of the genes in a population (which can cause a phenotype to occur, oftentimes referred to as “junk” DNA because it's the noncoding regions of a chromosome that do not produce a specific phenotype)

genotype

all the genes within an individual (or a subset of them) that causes a particular trait we’re interested in

gene

 a sequence of nucleotides that codes for a particular phenotypic trait (causes a particular phenotype to occur)

alleles

different versions of the same gene

ploidy

the number of sets of chromosomes that a cell has

haploid

1 set of chromosomes

diploid

2 sets of chromosomes

crossing over

occurs during meiosis I at the chiasma and non-sister chromatids will come together and exchange genetic information

transformation

(asexual reproduction) bacteria can open their pores and let in other bacterial DNA that was floating around—usually derived from dead bacteria—and will create a plasmid or incorporate itself into the host DNA.

transduction

(asexual reproduction) requires the activity of a virus—bacteriophage—the phage DNA that is inserted into the bacteria will code for a phenotype that grows more viral particles.

conjugation

(asexual reproduction) conjugation tube is formed by a bacterial cell that contains a plasmid and one that does not contain a plasmid in it

blending inheritance

prior to Mendel, scientists believed traits would “mix” (i.e. adding red and yellow together would make orange)

inheritance by acquired characteristics

the idea proposed by Lamarck (giraffes and neck length example) that offspring will directly inherit traits that their parents acquired prior to conceiving them

hemizygosity

a genetic state in a diploid organism where only one copy of a gene or chromosome segment is present instead of the usual two

Y chromosome

will determine the sex of the offspring and if it will be male (since we all start out as female, but if this is present then during gestation the offspring will become a male)

reciprocal cross

when the trait we are interested in is flipped based on the sex of the parent (i.e. T.H. Morgans initial experiment (i.e. the trait for white eyes was in the male parent in the F1 cross, but in the next cross it would be the female parent who has the trait for white eyes).

multiple allelism

despite an individual having 2 alleles per gene on their chromosomes, the rest of the population may have other possible alleles for the same gene

epigenetic effects

Environmental stressors permanently change the genetics of individuals, if this happens before offspring are born then they will inherit those changes too (very Lamarckian)

incomplete dominance

where a heterozygous genotype expresses an intermediate phenotype (similar to blending)

codominance

both genotypes are expressed, a combination of the two. (i.e. blood types, chicken feather patterns)

polygenic effects

a single trait is affected by many genes with the effects being additive. leads to continuous variation rather than an eithor/or situation.

pleiotropic effects

a single allele effects many traits

environmental effects

it’s important to distinguish how much of a trait is due to environmental pressures vs how much is strictly genetic