Biology Study Sheet

Importance of cell division: reproduction, repair, growth

Interphase: time between cell division, nucleus with DNA, normal activity, Cell grows copy of DNA. Prepares for division

Prophase: chromosomes thicken, shorten, group in pairs, nucleus dissolves, spindle fibers form

Metaphase: chromosomes line up in the middle of cell Anaphase: chromosomes split in half-moves to opposite sides of cell, spindle fibers shrink Telophase: new nucleus form around chromosome-half on each end. Cell starts to pinch in half Cytokinesis: cell completely half & cytoplasm splits in half, two new cells=)

Asexual: single organism produces identical off spring

Binary fission: splits into 2 off springs (bacteria)

Budding: small growth breaks off and creates new offspring (yeast)

Fragmentation: part breaks off and grows into new offspring (starfish)

Spore formation: parent produces pore that grows into identical organism (fern, mould)

Vegetative reproduction: plants produce 'runners' that grow new plants at end (spider plant)

Sexual-2 parents give genetic information that form a unique organism

1: conjugation: simplest form -Two bacteria exchange different genes then produce through binary fission

2. Separate sexes- when gamotes (egg+sperm) combine form a zygote

3. Hermaphrodites: mainly plants - Organisms can produce both male and female sex cells within the same body

DNA-Double Helix...adenine, cytosine, guanine, thymine, Controls what cells create, 2 parts: backbone and nitrogen bases. Genetic information-what your like.

Stages of Pregnancy-

First trimester-12 weeks: Heart, brain, limbs form, Skeleton forms into bone from cartilage, Internal organs begin to work, Fingers and toes can be seen...eyelids, toenails form, Fetus begins to move , Almost 10cm long, Fetus most at risk for birth defect at this time

Since baby is forming internal organs limbs brains and spine exposure to chemicals may prevent proper development, Damage often leads to miscarriage

Second Trimester: mother begins to show pregnancy, Hair grows, Can blink, hear, swallow and cry with its features, Fetus begins to swallow amniotic fluid, After 6 months fetus is 35cm and could survive if delivered at this time

Third trimester: Fetus begins to drop in position for birth near pelvic bones, Uncomfortable time for mother as the fetus takes up room and starts pushing her organs aside, All bones harden except skull, Once fetus is 37 weeks old it can breathe on its own when delivered and is considered full term.