Biology final

scientific method

A process of discovery that helps us to understand the natural world through exploration, testing ideas, community feedback, and analysis.

hypothesis

A proposed explanation that is based on a narrow set of observations

theory

A powerful explanation that is based on a wide set of observations and is strongly supported

scientific laws

Observations, not explanations.

reductionism

The process of taking a complex system apart to study its individual parts.

complex systems theory

The idea that the whole is greater than the sum of its parts, with new properties emerging from complex interactions.

monomers

Single chains that make up polymers.

enzymes

They facilitate chemical reactions within the body.

Mendel's law of segregation

pairs of alleles separate during gamete formation, with each gamete receiving one allele from each pair

Postzygotic isolating mechanisms 

Prevent hybrid offspring from being successful (after egg fuses with the sperm)

Prezygotic Isolating Mechanisms

Prevent successful formation of zygote (before egg fuses with the sperm)

• geographic isolation 

A prezygotic isolating mechanism when two species are separated by physical barriers

• Habitat isolation 

A prezygotic isolating mechanism where two species live in different habitats

Temporal isolation

A prezygotic isolating mechanism where two species breed at different times

Behavioral isolation

A prezygotic isolating mechanism where two species have different mating behaviors

• Mechanical isolation

A prezygotic isolating mechanism where two species are physically unable to mate because of differences in reproductive structures

• Gamete isolation 

A prezygotic isolating mechanism where the gametes of two species are incompatible

Hybrid mortality

A postzygotic isolating mechanism where hybrid offspring fail to survive

• Reduced hybrid viability 

is a postzygotic isolating mechanism where hybrid offspring are less viable than their parents

• Reduced hybrid fertility and hybrid breakdown 

are postzygotic isolating mechanisms that affect the fertility of hybrids and their next generations

Reproductive isolation

lack of gene flow between populations 

• Promotes speciation 

• The opposite of “gene flow” 

Speciation

a splitting event that produces two species 

• An accumulation of genetic differences between populations over time  

• Eventually results to the inability to interbreed

Species

Not a level of biological organization 

• Not really definable  

• It's a taxonomic classification:  

• It's the most specific, domain is the most general 

Definition: “type” of living thing based on characteristics 

Microevolution

• “short term” 

• Changes in the gene pool from one generation to the next 

Macroevolution

• “Long term” 

• Speciation: the formation of a new species  

Types of Natural Selection

including stabilizing, directional, and disruptive selection.

Stabilizing selection

• selection against the extremes 

• Loss of variation 

• Increased adaptation to a constant environment 

Directional selection

• selection against only one extreme 

• Adaption to a changing environment  

Disruptive selection

• either extreme is favored over intermediate 

• Separation of population into 2 distinct groups 

Is adaptation evolution?

No, adaptation is the RESULT of evolution, by natural selection

Adaptation

a useful trait increasing in the pop

evolution

changing the gene pool from one gen to the next

natural selection

mechanism that causes gene pool to change, can also prevent change

Mutation, gene flow, nonrandom mating, genetic drift, selection

the 5 mechanisms of evolution

nonrandom mating

individuals choose others due to specific preferences or relationships

mutation

change in the DNA sequence

must be heritable

gene flow

MIGRATION: movement of genes between populations

3. Can introduce new alleles 

4. Reduces variation btw populations 

5. Increases variation in within populations 

6. Slows, or prevents speciation 

Genetic drift:

random change in allele frequencies 

1. Increase variations btw populations 

2. Decrease variation within population 

selection

organisms with traits that better enable them to survive and reproduce tend to leave more offspring, thus increasing the frequency of those traits in the next generation.

survival related to phenotype or genotype

gene pool

the genetic makeup of a population

requirements of evoltuion

level of biological organization: population

need variation of a heritable trait in a gene pool

homology

similarities are inherited from a common ancestor (bones in a bat wing)

Analogy

Adaptations from having a similar environment (the wings of a bat)

Diploid dominant

the multicellular stage is on the diploid side

haploid dominant

the multicellular stage is on the haploid side (zygote doesn’t grow)

Alternation of Generations

multicellular on both sides of the lifecycle (ferns)

Sometimes fungi dont grow

True or false: Zygotes grow to produce a multicellular adult?

false

True or false: animals have a haploid dominant lifecycle

false

True or false: plant sporophytes are haploid

true

True or false: spores are haploid

Sometimes, true in animals false in plants or fungi

True or false: meiosis produces gametes

Fungi

the zygote doesn’t grow, it goes to meiosis and mitosis,

• Spores germinate and grow  

• Adults in fungi are haploid 

• Theres only 1 set of chromosomes in all those cells 

Bacteria, Eukarya, Archaea

the three domains of life

Bacteria

the most diverse individuals and species

archaea

extreme environments

eukarya

animals, fungi, plants, protists

Land plants

cellulose cell walls

alternation of generations

fungal diversity

every cell is on the surface of its body

eukaryotic

haploid dominant

animals

diploid dominant

humans are chordates

Prokaryotes

no nucleus

no membrane bound organelles

circular chromosomes

smaller

eukaryotes

with nucleus

membrane bound

linear chromosomes

larger

sexual reproduction

meiosis + fertilization

viruses

parasitic biochemicals

genetic material with protein coat (capsid)

Are viruses alive

Yes and no

• Not cellular,  

• not move on their own,  

• no metabolism or homeostasis 

• No reproduce on their own 

 

• Biomolecules 

• Have genetic info 

• Genetic code same as living things 

• Evolve 

Systematic biology

Taxonomy and Phylogeny

Taxonomy

name, discover, describe, classify life

domain is the most general, species is the most specific

phylogeny

a hypothesis of evolutionary relationships

Phylogenetic tree

a hypothesis based on a given set of data 

• Graph of evolutionary relationships  

• An explanation of the observed patterns of similarities and differences. 

• Node: hypothetical common ancestor ,Most important part: has information 

locus

location of a gene on a chromosome

phenotype

physical appearance

genotype

genetic makeup

linkage

traits carried on the same chromosome cannot assort independently, resulting in fewer possible combinations in the haploid cells

Meiosis

Result: 4 different haploid cells

makes gametes (sperm and egg) - haploid

duplicated chromosomes line up in pairs

the zygote is the first cell of the next generation after fertilization - diploid

Meiosis 1

line up and homologous chromosomes separate

meiosis 2

sister chromatids separate

Mitosis

injury repair, growth, replacement

• duplicated chromosomes line up in the middle

• sister chromatids separate

• results in two identical cells

• does not change the number of chromosomes

Homologous chromosomes

not identical, pair of sister chromatids XX, one form each parent

Histone

type of organizational/structural protein found in chromosomes

nucleosomes

the unit that includes the DNA wrapped around the histones

chromatin

the state of organization of chromosomes

unwound

can be used to produce proteins, uses DNA

independent assortment

which way the chromosomes line up is random

pairs of alleles

tRNA

carries amino acids

proteins

structure and function

function: enzymes (help chemical reactions

chromosome

a DNA molecule or “hereditary unit”

• tightly packaged DNA

• only found in cell division

• cannot be used by cell to produce proteins

homologous chromosomes

not identical, one from dad one from mom, but same genes at same location, may have different alleles 

Homozygous

alleles at a specific locus are identical in a pair of chromosomes 

ex: gg or GG

Heterozygous

ex: Gg

allele

alternate form of a single gene and found at the same locus on homologous chromosomes

gene expression = protein synthesis

the sequence of a gene determines the amino acid sequence of a protein 

Transcription

copying the gene from DNA to RNA

Translation

Building the protein from RNA —— Protein

gene

segment of DNA molecule that stores information

indirectly determines traits

blueprint for making our proteins (proteins control our traits)

entropy

measure of how much energy in a system is dispersed

to maintain organization and complexity

requires: energy flow and nutrients cycles

energy

the ability to do work

nutrients

elements (the parts)

autotrops

producersh

heterotrophs

consumers

Metabolism

all the chemical reactions required to keep you alive

homeostasis

the internal conditions are balanced, favor cell survival/metabolism