Bio 103 Exam 3 (McMullen)

Interphase

cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

chromosomes are replicated, each consisting of 2 identical chromatids held together at the centromere

G1 phase

the cell grows in size and organelles double in number

S phase

DNA replication ("S"= synthesis)

G2 phase

cell growth, production of enzymes and other proteins

two categories of mitosis (eukaryotic cell division)

1. karyokinesis (division of cell nucleus)
2. cytokinesis (division of cytoplasm)

prophase

1. chromatin condenses to form chromosomes

2. centrosomes move apart and form polar spindle fibers (made of microtubules)

3. nuclear membrane and nucleoli disappear

4. kinetochore fibers attach to proteins called kinetochores within the centromere of each chromatid pair

centromere

Area where the chromatids of a chromosome are attached

chromatid

one of two identical "sister" parts of a duplicated chromosome attached at the centromere

chromatin

the unorganized mass of DNA and histone proteins within the nucleus

kinetochore

A specialized region on the centromere that links each sister chromatid to the mitotic spindle.

metaphase

the kinetochore and its fibers move the chromosomes to the equatorial plate where they form a line

anaphase

• 1. chromatids separate and move to opposite poles
  2. the centromeres move first and the arms drag behind

• once the chromatids have separated, they are called daughter chromosomes

what are the longest and shortest phases of mitosis

prophase is the longest; anaphase is the quickest

telophase

1. the spindle fibers break down
2. nuclear membranes, nucleoli, and chromatin reappear

cytokinesis in plant cells

1. cell plate forms from inside out by vesicles produced by dictyosomes
2. cell plate becomes middle lamella
3. cell wall is laid down

the result of mitosis or duplication division

daughter cells that are identical to one another genetically

what allows plants to reproduce asexually?

rhizomes, stolons, and plantlets

rhizomes

horizontal underground stems (grasses, irises) ex. crabgrass

stolons “runners”

horizontal above ground stems (ex. strawberries)

plantlets

miniature plants on special leaves that produce new plants at a later time (formed at the margins of leaves) (ex. mother of thousands)

what allows animals to reproduce asexually

fragmentation, budding, and fission

fragmentation

a portion of an individual can break free and regenerate an entire organism (ex. sponge)

budding

a miniature offspring forms on the parent and then breaks off (ex. hydra)

fission

the separation of a parent into two or more individuals of roughly equal size (ex. sea anemone)

what are some animals that reproduce asexually

sponge, sea anemone, hydra

advantages of asexually reproduction

1. create numerous offsprings quickly
2. quickly colonize a new habitat
3. can reproduce in isolation (no mate)
4. perpetuates successful combinations of genes
*most advantageous in a stable, favorable environment

meiosis

the process of cell division in which the chromosome number is reduced from the diploid number (2n) to the haploid number (n)**reduction division

sexual reproduction (EUKARYOTES)

gamete formation (meiosis) and syngamy (fertilization)

syngamy (fertilization)

The fusion of two gametes to form a diploid zygote in fertilization.

meiosis i

separates homologous chromosomes

meiosis ii

sister chromatids separate

prophase i

1. the chromosomes become visible and group in pairs (separate)
2. the nuclear envelope breaks down and pairs synapse into tetrads
3. crossing-over occurs (recombination)

tetrads

synapse of homologous pairs; four chromatids from homologous chromosomes

metaphase i

tetrads line up in the middle of the cell

anaphase i

homologues separate and move to opposite poles ; sister chromatids stay together

telophase i

1. homologous chromosomes have reached the poles; nuclear envelopes may/not form and cytokinesis may/not occur
2. newly forming cells are haploid; each chromosome has two non-identical sister chromatids

interkinesis

period of time between meiosis I and meiosis II during which no DNA replication takes place.

prophase ii

1. the nuclear envelope breaks down and spindle fibers reform
2. starting cells are the haploid cells made from meiosis i

metaphase ii

the chromosomes line up on the equatorial plane

anaphase ii

sister chromatids separate and new daughter chromosomes move to opposite poles

telophase ii

1. the spindle fibers disappear, and a nuclear membrane forms around each set of chromosomes
2. newly forming gametes are haploid
3. cytokinesis takes place

results of meiosis

4 haploid daughter cells; each has 25% of DNA and half the amount of chromosomes

fertilization of egg and sperm result in...

diploid offspring with 50% of DNA and homologous pair of chromosomes

importance of meiosis

genetic variation in species
** in humans: over 64 trillion different combinations w/o considering crossing over

green plants

• green algae

• nonvascular plants

• seedless vascular plants

• gymnosperms (seed vascular plants)

• angiosperms (seed vascular plants)

land plants

nonvascular plants, vascular seedless plants, gymnosperms (seed vascular), angiosperms (seed vascular)

most primitive green plant

green algae

green plant synapomorphies

chlorophyll b, grana in chloroplasts, cellulose & hemicellulose are major cell wall components, plasmodesmata, and starch is the food storage product

plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

differences between land plants and green algae

gametangia, diploid embryo, and cuticle

gametangia

outer, sterile layer of protective plants

diploid embryo

grows into a multicellular, sporophyte generation

cuticle

outer, waxy covering which prevents them from losing water since they have to live on land

most primitive LAND plants

nonvascular plants: liverwort, hornwort, moss

once thought to cure liver disease

liverwort (according to the Doctrine of Signatures)

hornworts

1. mature sporangium releases spores
2. spores become gametophyte

moss

most advanced nonvascular plant due to stomata; has hydroids and leptoids (similar to xylem and phloem)

stomata are often present on the sporophytes

haploid generation

gametophyte

diploid generation

sporophyte

sporic meiosis (sexual reproduction in land plants)

alternation of generations between haploid and diploid generations (produces spores)

vascular plants

• have organs (roots, stems, and leaves)

• vascular tissue system (xylem and phloem)

• dominant sporophyte generation

• lignin comprises the secondary cell walls of certain cells

seed plants

have seed = embryo, nutritive tissue, seed coat
2 types: gymnosperms and angiosperms

gymnosperms

A plant that produces seeds that are exposed; no fruits, no flowers
ex: pine, conifers, male cones, pollen grains, female cones

pine

males cone (pollen grains), female cone (ovule)

angiosperms (vessel seed)

1. flowers
2. fruits
3. double fertilization (endosperm)
4. 3 nucleate

largest angiosperm

eucalyptus

smallest angiosperm

wolffia (duckweed)

two classes in phylum anthophyta

monocotyledones and eudicotyledones

characteristics of moncots

1. one cotyledon apart of each embryo
2. flower parts in 3's or multiples of 3
3. parallel leaf venation
4. scattered stem vascular bundles

monocot examples

coconut palm, trillium, rice, wheat, corn

characteristics of dicots

1. 2 cotyledons apart of each embryo
2. flowers in 4's or 5's
3. distinct ring of stem vascular bundles
4. net leaf venation

examples of dicots

cinquefoil, daisy, strawberry, poppy, cactus, lima beans

typical flower parts

ovule, receptacle, sepal, stamen (anther/ filament), petal, pistol (stigma, style, ovary)

ovule

female reproductive structure of a seed plant where the haploid egg develops; becomes seeds

receptacle

The base of a flower; the part of the stem that is the site of attachment of the floral organs.

sepal

A leaflike structure that encloses the bud of a flower; for protection

stamen

the male reproductive organ of a flower

anther

the part of a stamen that contains the pollen.

filament

the stalk of a stamen; supports the anther

petal

attracts pollinators

pistil

female reproductive organ of a flower

stigma

where pollen lands

style

The stalk of a flower's carpel, with the ovary at the base and the stigma at the top; "pollen tube"

inflorescence

cluster of flowers on a plant
(panicle, spike, raceme, head, catkin)

panicle

a branched, indeterminate inflorescence with flowers on short stalks along the axis (most complex)

spike

single stalk with flowers directly on the stalk (simplest)
ex: corn

head

outer (ray) and disc (inside) flowers

catkin

slim cylindrical flower cluster with few or no petals; hanging arrangements

pollination syndrome

pollinators and flowers coevolve; flowers and their pollinators have adapted to each other

beetle pollination

• eat their way through petal with their jaws (so ovules are found deeper)

• pollinate one large flower (magnolia or dogwood) or inflorence

• clumsy, primitive, unsophisticated

bee pollination

1. white or yellow flowers

2. nectar guides

3. some orchid flowers resemble female bees that male bees copulate with them

4. nectar robbing: no pollination occurs but bees get nectar

5. adult bees eat nectar larvae feed on pollen

fly pollination

1. foul odor
2. pollen sticks to body

moth pollination

1. active at night
2. pale flowers; strong odor

butterfly pollination

1. attractants: brightly colored flowers
2. rewards: abundant nectar (head flowers like sunflowers)

bird pollination

1. bright colors (reds); no odor, more nectar
2. pollen attaches to beak and feathers

bat pollination

1. fermented or musty smell

2. mostly in tropics

3. more nectar

4. pale or white flowers

5. petals or tear resistant

wind pollination (abiotic- nonliving pollination)

1. pollination of plants by means of pollen carried on the wind
2. no odor, no petals, no nectar
ex: corn

water pollination

pollen floats on water between flowers

three types of fruits

aggregate, multiple, simple