Life Science

Directional selection

Individuals that have a more extreme version of a trait have greater fitness than those with the average version of a trait

Disruptive selection

Either extreme variation of a trait has greater fitness than individuals with the average version of the trait

Stabilizing selection

Individuals with an average form of a trait have the highest fitness

Prophase

Chromosomes condense, nuclear membrane breaks down, spindle fibers form

Metaphase

Chromosomes line up in the middle

Anaphase

Sister chromatids separate and move apart

Telophase

Nuclear membrane reforms, chromosomes uncoil (two nuclei)

Cytokinesis

Cytoplasm divides, two cells officially separate

Cytoskeleton parts

Microfilaments, microtubules, intermediate filaments

Microfilaments

Smallest, made of actin, cell shape, cell movement

Microtubules

Cell movement, cell division (spindle fibers)

Intermediate filaments

Strength, stability, anchor organelles

(Like shock absorbers)

Nondisjunction

When a cell can have too many or too few chromosomes because a chromosome didn’t separate properly in anaphase

Heterochromatin

Tightly-packed/condensed DNA, inactive DNA

Euchromatin

Loose DNA, active, occurs during interphase or transcription

Histone

Proteins that DNA wraps around, helps pack DNA strands into the nucleus

Bryophytes

Non-vascular plants (no xylem or phloem), live mostly in moist environments, e.g. mosses, liverworts, hornworts

Ferns

Vascular, seedless, reproduce using spores, have a sporophyte dominant life cycle

Fronds

Fern leaves, have a fiddlehead shape

Do seedless plants need water in order to fertilize?

Yes

Sporangia

Structure that produces and contains spores

Genotype

Genetic makeup

Phenotype

Characteristic resulting from the genotype and environment

Allele

an alternative version of a gene cause by mutation

Dominant allele

Gene whose trait is expressed even when there is only one copy is present

Recessive allele

Doesn’t produce a trait at all when there is only one copy present

Homozygous genotype

Two of the same alleles for a gene (TT, tt)

Heterozygous genotype

Two different alleles for a gene (Tt, Hh)

Mendel’s 3 laws

Law of segregation, Law of dominance, Law of independent assortment

Mendel’s Law of Segregation

Each individual has two alleles per gene, during meiosis the alleles separate, leaving each gamete with one allele

Mendel’s law of dominance

When an organism has two different alleles for a trait: one allele can mask the expression of the other, the expressed trait is the dominant phenotype

Incomplete dominance

Heterozygote shows a blend (red x white = pink)

Codominance

Both alleles are fully expressed (AB blood type)

Mendel’s law of independent assortment

Knowing one trait doesn’t predict the other

Cartilage is which type of tissue?

Connective

Glycine

Smallest amino acid

Valine, Leucine, Isoleucine

Amino acids important for muscle proteins

Methionine

Beginning amino acid for protein synthesis

Serine and Threonine

Involved in enzyme activity

Cysteine

Contains disulfide bonds, helps proteins fold

Gram stain

Staining method used to divide bacteria based on cell wall structure

Gram-positive

thick peptidoglycan cell wall, stains purple, ex: Strep, staph

Gram-negative

have a thin peptidoglycan wall, outer membrane, and stain pink

ex: e coli

Heterosis

Crossing of two pure lines (homozygous) to create a hybrid, hybrids have traits stronger or better than both parents (more rigorous)

DNA base pairings

A-T

C-G

Purines

Two rings

Adenine and guanine

Pyridimines

One ring

Cytosine, thymine, uracil

Gene amplification

Alters genome by copying a gene multiple times

Transposons

Genes that move to new positions in DNA, can change the sequence of a somatic cell

Helicase

Enzyme that breaks down hydrogen bonds between base pairs of DNA for DNA replication by unwinding it

two types of active transport

primary and secondary

primary active transport

uses chemical energy directly that comes from ATP

secondary active transport

does not use ATP directly, uses electrochemical gradient created by primary active transport

Reproductive isolation

anything that prevents two populations from producing fertile offspring

prezygotic isolation

reproductive isolation that occurs before fertilization

postzygotic isolation

reproductive isolation after fertilization

Geographic isolation

prezygotic isolation where populations are separated due to physical barriers

temporal isolation

prezygotic isolation where both species mate at different times

Behavioral isolation

prezygotic isolation where the species have different mating methods

mechanical isolation

prezygotic isolation where the body parts are physically incompatible

gametic isolation

prezygotic isolation where the sperm and egg cannot fuse

Reduced hybrid viability

hybrid forms but is weak or dies early

reduced hybrid fertility (genetic isolation)

hybrid survives but is infertile

hybrid breakdown

first generation is okay, later generations are weak or infertile

allometric growth

different parts of an organism grow at different rates

isometric growth

parts of an organism grow at the same rate

gel electrophoresis

lab technique used to separate DNA fragments by size by using electricity

negative DNA moves to the positive side

smaller fragments move farther from their staring position

abscission

natural process by which plants shed parts

Senescence

biological aging of a cell, tissue, or organism

cornea

clear outer layer of eye

bends/refracts light

iris

colored part of eye

controls pupil size, which regulates how much light enters the eye

pupil

opening in the center of the iris where light enters

lens

focus light onto retina, changes shape to focus near vs. far

retina

light-sensitive inner layer, contains rods and cones

rods

detect light/dark

cones

detect color

optic nerve

carries signal from the retina to the brain

fovea

area with highest cone concentration, sharpest vision

blind spot

where optic nerve exits, no rods or cones

sclera

white of the eye, protection and shape

myopia

image focuses in front of retina, nearsighted

hyperopia

image focuses behind retina, farsighted

histamine

chemical released by mast cells during an allergic reaction

fat-soluble vitamins

vitamins stored in fat (A, D, E, K)

Vitamin A

(retinol, beta-carotene) used for night vision, healthy skin, immune system

lack of Vitamin A causes:

night blindness, dry eyes (xerophthalmia)

Vitamin D

helps absorb calcium, bone growth and strength

Lack of Vitamin D causes:

Rickets, Osteomalacia

Vitamin E

Antioxidant, protects cell membranes

Vitamin K

blood clotting

lack of vitamin K causes:

excessive bleeding

water-soluble vitamins

Vitamin B and C

Vitamin B1 (Thiamine)

energy metabolism, nerve function

lack of B1 causes: Beriberi (nerve and heart issues)

Vitamin B2 (Riboflavin)

energy production

lack of vitamin B2 causes: sore throat, cracks at corners of mouth

Vitamin B3 (Niacin)

energy metabolism

lack of B3 causes: diarrhea, dementia, dermatitis

Vitamin B6

amino acid metabolism, brain development

lack of B6 causes: anemia, nerve issues

Vitamin B9 (Folate)