Cell Division/DNA in the cell:

Basic Vocabulary

Chromosomes: how to organize DNA (like aisles at Target)

Chromatid: each strand of a duplicated chromosome

Centromere: the area where each pair of chromatids is joined

Centrioles: tiny structures located in the cytoplasm of animal cells that help organize the spindle

Spindle: a fanlike microtubule structure that helps separate the chromatids

Eukaryotic Cell Cycle

Eukaryotic Cell Cycle: 2 major parts - Interphase (between 2 cell division) G1, S, G2 - Cell Division (divides cell into 2) M phase

G1 phase: INTERPHASE Cell Growth- cells increase in size, synthesize new proteins or organelles

S phase: INTERPHASE DNA Replication- new DNA is synthesized, chromosomes are replicated

G2 phase: INTERPHASE Preparing for Cell Division- many of the organelles and molecules required for cell division are produced

M phase: CELL DIVISION, occurs in two stages [Mitosis (division of cell Nucleus) —> Cytokinesis (division of cytoplasm)] - prophase, metaphase, anaphase, telophase, cytokinesis

Prophase: cell gets ready to divide nucleus, duplicated chromosome condenses and becomes visible, centrioles move to opposite sides of nucleus to help the organize the spindle, spindle forms and DNA strands attach at centromere

Metaphase: chromosomes lines up in the middle of the cell, spindle fibers connect the centromere of each chromosome to the two centrioles

Anaphase: centromeres are pulled apart and the chromatids separate to become individual chromosomes, chromosomes separate into 2 groups near the poles of spindle

Telophase: chromosomes spread out in a tangle of chromatin, nucleus re-forms around each cluster of chromosomes, spindle breaks apart, and nucleus becomes visible in each daughter nucleus

Cytokinesis: membrane is drawn in until cytoplasm in pinched in 2 equal parts, part contains own nucleus and organelles

Cell Division in Plant Cells: difference- cell plates instead of membrane, cell plates —> cell walls

Regulating the Cell Cycle

Cyclins: a family of proteins that regulate the timing of the cell cycle in eukaryotic cells

Regulatory Proteins

Internal regulators: respond to events inside a cell- allow the cell cycle to proceed only once certain processes have happened inside the cell

External regulators: respond to events outside the cell- cells speed up or slow down the cycle

Growth factors: external regulators that stimulate the growth/division of cells, are important during eukaryotic development / wound healing

Apoptosis: process of programmed cell death- plays a role in development by shaping the structure of tissues / organs in plants and animals (EX: shape of a mouse’s foot is that way because toes undergoes apoptosis during tissue development)

Cancer: body cells lose the ability to control cell growth- cancer cells divide uncontrollably to form a mass of cells (tumor)

Benign tumor: no cancerous, does not spread healthy tissue

Malignant tumor: cancerous, spread of cancer cells is metastasis (absorb nutrients needed, block nerve connection, prevent organs from functioning)

Treatments (for cancers and tumors): chemotherapy, radiation, surgery

Causes (of cancers and tumors): by defects in genes that regulate cell growth / division - some sources of gene defects are smoking, radiation, defective genes, viral infection - damaged p53 gene is common… causes cell to lose the information needed to respond to growth signals

Telomeres: like an angle of a chromosomes, telomeres get shorter as the chromosomes keeps dividing

Meiosis

Meiosis: cell division that forms gametes (egg and sperm cells), gametes have half the number of chromosomes (23 for humans)

2 Divisions of Meiosis: Meiosis 1 & 2

Homologous Chromosomes: pair of chromosomes (maternal and paternal) that are similar in shape and size, carry genes controlling the same inherited traits, humans have 23 pairs of homologous chromosomes

Sex Chromosomes: code for the sex of offspring, 2 X chromosomes = female, 1 X chromosome + 1 Y chromosome = male

Interphase of Meiosis: Similar to Mitosis (haha I’m making you look back 😈 )

Meiosis 1: cell division reduces chromosome number by head (can only give half of DNA)

Four phases of Meiosis 1: prophase 1, metaphase 1, anaphase 1, telophase

Prophase 1 (Meiosis 1): crossing over segments of no sister chromatids break and reattach to the other chromatid (very good— genetic diversity)- like playing footsies

Metaphase 1 (Meiosis 1): Similar to Mitosis

Anaphase 1 (Meiosis 1): Similar to Mitosis

Telophase 1 (Meiosis 1): Similar to Mitosis

Meiosis II: Similar to Mitosis— same process (telophase II makes 4 haploid daughter cells)

Fertilization: fusion of sperm and egg to form zygote

Spermatogenisis: making of sperm

Oogenisis: making of egg

Genetics

Trait: specific characteristic of an individual (MAY VARY)

True breeding: would process offspring with identical traits to themselves (the traits of each successive generation would be the same)

Gene: factors that are passed from parent to offspring

Allele: different forms of genes

Mendel’s 2 Principles

Principle 1: an individual’s characteristics are determined by factors that are passed down from one paternal generation to the next

Principle 2: Principle of Dominance- this principle states that some alleles are dominant / some are recessive / even if there is 1 dominant allele, the organism will show the dominant trait (capital) / in order to see recessive, there must be NO dominant traits (lowercase)

Gametes: sex cells

Probability: likelihood that a particular event will occur

Homozygous: organism that have 2 identical Allels for a particular gene (TT or tt)

Heterozygous: organisms that have 2 different Allels for the same gene (Tt)

Phenotype: physical traits

Genotype: genetic makeup

Independent Assortment: Mendel performed an experiment that followed two different genes as they passed from 1 generation to the next

Principle of Independent Assortment: genes for different traits can segregate independently during gamete formation

Incomplete Dominance: one allele is not completely dominant over another / the heterozygous is a MIX

Multiple Alleles: a gene with more than 2 alleles is said to have multiple alleles (more than 2)

Polygenic Traits: traits that are controlled by two or more genes (many genes) / often show a wide range of phenotypes (EX: skin color)

Sex-linked Inheritance: some traits are located on the sex chromosomes so the inheritance of these traits depends on the sex of them parent carrying the trait / affects males more than females / some associated with disorders (male pattern baldness or reel-green color blindness)

Pedigrees: genetic family tree that show how prevalent a trait is in a family unit from generation to generation (square = males, circles = females, colored-in = has the trait, half-colored = carrier for recessive)

Autosomal Dominant Inheritance: refers to those situations in which a single copy of an allele is sufficient to cause expression of a trait (EX: progeria, Huntington’s disease)

Genes and the Environment: the characteristics of any organism are determined by the genes that organism inherits and the environment it lives in.

Protein Synthesis

Central Dogma of Biology: DNA —> RNA —> Protein

DNA stores information by order of nucleotides: A = T C = G

Transcription: copy / DNA —> RNA

Translation: RNA —> Protein

Codon: 3-letter “word” in mRNA / consists of 3 consecutive bases that specify a single amino acid (AMINO ACIDS MAKE UP PROTEINSSS)

Process of Transcription: RNA polymerase makes mRNA —> mRNA has a message from DNA… it leaves the nucleus and goes in the cytoplasm

Reading mRNA (between): ribosomes (attaches to mRNA) reads message —> tRNA has an anticodon and places the corresponding amino acid

Process of Translation: polypeptide chain continues to grow until the ribosome reaches a “stop” code on on the nRNA molecule / translated into sequences of amino acids on ribosomes / tRNA carries individual amino acids to ribosome according to anticodon

Mutations in DNA

Gene mutations (point mutations): produces changes in a single gene ( 1 chromosomes)

Substitutions: GENE MUTATIONS / substitute one base pair for another

Insertion/Deletion: GENE MUTATIONS / inserting extra nucleotide/take one nucleotide out

Chromosomal mutations: involves changes in the number or structure of chromosomes

Deletion: CHROMOSOMAL MUTATION / deletion of chunk of genes

Duplication: CHROMOSOMAL MUTATION / 2x

Inversion: CHROMOSOMAL MUTATION / switching, flipping

Translocation: CHROMOSOMAL MUTATION / rearranging (getting letters from another source)

Mutagen: occurs naturally mistakes

Protein Folding: Primary, Secondary, Tertiary, Quaternary

Evolution (you’re close to finishing! 😄 )

Evolution involves changes in the _____ of a _______ !: genes, population

Gene pool: all the genes in a population

Allele frequency: how often “B” and “b” show up

Hardy-Weinberg Law: if these conditions are met, the allele frequencies are NOT changing, so the population stays constant = NO evolution!! — no mutations, populations are large, mating is random, no immigration of other genes, no selection pressures.

What causes evolution?: Mutations, small populations, non-random mating, gene flow, natural selection

Population: group of the same species living in the same area

In small populations, allele frequencies can change drastically!: genetic drift

Bottleneck: event occurs —> reduces size of population —> only those left surviving will reproduce —> changes the population

Founder effect: a few colonize a new area —> only THEIR genes in the population —> could lead to new species! 😄

Species: a group that can mate and have fertile offspring

Allopatric Speciation: barrier PHYSICALLY separates the population

Sympatric Speciation: specialization to a specific habitat within the same location

Pre-mating Isolation Mechanism: before mating, prevent it (EX: breeding @ different times, incompatible reproductive structures, different courtship rituals)

Post-mating Isolation Mechanism: after mating, unfit offspring (EX: cannot fertilize, hybrids don’t survive, hybrids are sterile)

Sexual Selection: Females (usually) choose which males to mate with, only their genes go on to the next generation

Gene flow: Immigration / Emigration of individuals happens all the time, causing genes to MIX together!

Stabilizing Selection: middle phenotype is best, so that increase over time (EX: height- bell curve) (EX: Sickle cell anemia and Malaria)

Directional Selection: one of the extremes are the best, so the population shifts in one direction (EX: speed)

Disruptive Selection: both extremes are good and the midd is bad (EX: peppered moths)

Hardy Weinberg EQUATION :’) (HWE for future reference in these notes): p Squared + 2pq + q squared = 1

HWE - p: dominant allele

HWE - q: recessive allele

HWE - p squared: frequency of AÀ

HWE - q squared: frequency of aa

HWE - 2pq: frequency of Aa

Adaptations: structures or behaviors that help an organism survive and / or reproduce!

Morphological (anatomical) adaptations: Camouflage (blend in with surroundings), Mimicry (look like something you’re not), Defense Mechanisms (defend yourself from predators)

Physiological (internal) adaptations: poisons, temperature regulations

Behavioral: Sexual selection, tool use, hibernation / migration

Coevolution: when 2 species evolve in response to one another / Work together = mutualism / “Arms race” predator & prey

Main Evidence to support Evolution!: Biogeography, Homologous Structures, Similar Embryos, Molecular / DNA

Biogeography: Fossils = dead preserved organisms / if organisms live in similar environments —> similar selection pressures —> similar features!

Homologous Structures: Similar bones = same ancestor —> must share DNA

**Analaguos Structures: different ancestors bust same function

Vestigial organs: No effect on survival anymore, but must have before or why would we have them??? (EX: Appendix)

Similar Embryos: In early development, species look the same! (Must share DNA / proteins) (Must have homologous structures!)

Molecular / DNA: Many similar genes across species / more genes shared = more closely related

Cladograms: organize life based on DNA / evolution

Binomial nomenclature: kingdom —> phylum —> class —> order —> family —> genus —> species

Ecology

Ecology: study of organism and their interaction with each other and with their environment

Population: same species, same area

Community: all populations living in the same area

Ecosystem: all of the communities and non-living things in an area

Biosphere: all Earth’s ecosystem combined

Abiotic: non-living things

Biotic: living things

Almost all organisms use the _____ stored in food to power their ______ processes: energy, life

What is the source of energy for all organisms?: THE S U N

Energy flow: Sun —> photosynthesis organisms (producers) —> consumers —> decomposers

Food chain: simple diagram of energy movement in an ecosystem, each organism represents a different trophic level or feeding level, illustrate predator-prey relationships

Biomagnification: toxins increase up the food chain

Producer: photosynthetic organism that makes own food (autotrophs)

Consumer: eats other organisms (heterotrophs)

Decomposer: consumes dead organisms and organic waste (recycle nutrients)

Herbivore: eat plants (primary consumers)

Carnivore: eat other animals (secondary consumer)

Omnivore: both plants and animals

Scavenger: carnivores that eat animals that are already dead

Pyramid of Energy: depicts the energy transfer from one trophic / feeding level to the next, only 10% of energy is transferred to the next level

Niche: specific role played by an organism (possible for different species to live in the same area and each occupy a different niche) (Only one species can occupy a niche in a community but many can occupy the same habitat) (if two species occupy the same niche, it leads to competition)

Competition: the struggle for limited resources (interspecific - between different species / intraspecific - between same species) fight over food, water, shelter, mates

Predation: when one individual (the predator), captures, kills and consumes another (prey)

Mutualism (Symbiosis): both organisms benefit from the association

Commensalism (Symbiosis) one organism benefits and the other one is neither helped or harmed

Parasitism: one organism benefits (the parasite) and one is harmed (the host)

Keystone species: a species that has usually large effect on an ecosystem

What increases a population?: birth, immigrants

What decrease a population: death, emigrants

Growth rate: (birth - deaths) + (immigrants - emigrants)

Population size: number of individuals of one species living together in a specific area.

Population density: a measurement of population per unit area

Population distribution: the pattern of where organisms live (RANDOM, UNIFORM, CLUMPED)

Population sex ratio: ratio of males to females

Population age structure: a graphical illustration that shows the distribution of various age groups in a population

Growth type-Exponential/J curve: growth rate becomes ever more rapid in proportion to the growing total number/size

Growth type-Logistic/S curve: occurs when the growth rate decreases as the population reaches carrying capacity (maximum number of individuals the environment can support)

Density-dependent Limiting Factor: factors that will limit a large population from growing larger (EX: reproductive barriers/predators)

Density-independent Limiting Factor: factors that will limit the growth of a population regardless of the size (EX: natural disasters)

Energy flows through ecosystems and nutrients cycle!

Carbon is found in every living thing, never lost/used up —> just transformed into something else!

Forms of Carbon in Atmosphere, Hydrosphere, Geosphere, Biosphere

HIPPCO: Habitat Loss, Invasive Species, Population, Pollution, Climate Change, Overexploitation