AP Biology - Meiosis; Mitosis; Gene Control; Viruses

Cell Cycle

Formed from dividing parent cell until its division into 2 cells

Genome

an organisms complete set of genetic information

Gametes

Sperm and Egg cells

Haploid & symbol

gamete with 23 chromosomes; n

diploid

cells with 46 chromosomes

Structure of duplicated chromosomes

2 sister chromatids attached by a centromere

2 sister chromatids

have identical DNA sequences

interphase

90% of the cell cycle

G1 phase

cell grows while carrying out normal cell function

S Phase

DNA replication ocures

G2 Phase (2)

prepares for division and cell grows more

Prophase (3)

chromatins become more tightly coiled into chromosomes; nucleoli disappears; the mitotic spindle forms in cytoplasm

Chromatin

mixture of DNA and protein that form chromosomes

Prometaphase

nuclear envelope beings to fragment and allows microtubules to attach to chromosomes

Centromere

contains protein kinetochores on each chromatid which the microtubules attach

Metaphase (2)

microtubules move chromosomes to the metaphase plate at the equator of cell (spindle); centrioles moved to opposite poles and ride along on the developing spindle

Centrosomes

have 2 centrioles

Anaphase (3)

sister chromatids start to separate; cells elongates; opposite ends contain complete sets of chromosomes

Telophase (2)

nuclear envelopes reforms around sets of chromosome at the end of cell

Cytokinesis in plant cells

cell plate forms and divides cytoplasm

Cytokinesis in animal cells

cleavage furrow forms and divides cytoplasm

G1 Checkpoint (2)

primary decision point; if cell receives go signal it divides if it doesn’t, it goes to G0 where tie cell is working but not dividing

Kinase

protein enzymes that control the cell cycle

Cyclins

regulatory proteins

Cdks (2)

cyclin dependent kinases; activates or inactivates proteins (when bounded to cyclins)

MPF

needs enough MPF to continue mitosis

Density Dependent inhibition

crowded cells stop growing

Anchorage dependence

cells must attach to substrate and touch sensor receptors

proto - oncogenes

cause cancers when switched on

Tumor Suppressor Genes

if OFF can cause cancer

Locus

location of gene on chromosomes

Somatic cells

cells that aren’t gametes (each cell has 46 chromosomes)

Karyotype

picture of its complete set of chromosomes thats arranged from largest to smallest

Homologous chromosomes

both chromosomes of each pair carry genes that control same inherited characteristics

autosomes

nonsex chromosomes

zygote

fertilized egg

results of meiosis

4 daughter cells

interphase of meiosis

chromosomes copy itself

Prophase 1

chromosomes condense and 2 sister chromatids attach at their centromeres

Synapsis (prophase 1)

joining homologous chromosomes along their lengths to form tetrads

crossing over (prophase 1)

DNA from one homologue cut and exchange DNA from other homologue → increase genetic variation

metaphase 1

homologous pairs of chromosomes lined up at metaphase plate and microtubules attach to prepare to pull apart

Anaphase 1 (2)

spindle move chromosomes to opposite ends; sister chromatids remain attached (2 chromosomes strands)

Telophase 1

each pole has 23 chromosomes and each chromosome has 2 chromatids attached

Cytokinesis 1

division of cytoplasm

Prophase 2

spindle apparatus forms and sister chromatids move towards metaphase plate

metaphase 2

chromosomes are lined up and are prepared to move to end of cells

anaphase 2

centromeres of sister chromatids separate and individual chromosomes move to opposite ends of cell

telophase 2

chromatids are at end of cell; nuclei reappears

cytokinesis 2

cells divide and each of the 4 daughter cells has 23 chromosomes

independent assortment

homologous chromosomes line up on metaphse plate and pair in any combination

nondisjunction

chromosomes dont separate during anaphase 2 and a daughter cell has extra chromosomes

Virus structure (4)

nucleic acid; capsid; some have viral envelopes ; only reproduce in host cell

bacteriophages

viruses that infect bacterial cells

Lytic Cycle (2)

ends in the death of host cell through rupturing; DNA gets injected into host cell and creates copies of viral DNA to create multiple copies of the virus

Lysogenic Cycle

bacteriophages DNA becomes incorporated into host cells DNA and replicates along hosts genome

Retrovirus

RNA virus that se enzymes to reverse transcriptase to transcribe DNA from an RNA template; host cell transcribes viral DNA to RNA to make viral proteins

Viroids (2)

circular RNA that infect plants; cause errors in regulatory system that control plant growth

Prions

misfolded proteins that cause misfolding of normal proteins in animal species

Operon structure (3)

operator that controls access of RNA polymerase to genes; promotor that RNA polymerase attaches; genes that code for enzymes produced by operon

Regulatory Genes (2)

repressor proteins that bind to operator site; RNA polymerase is blocked from functioning

Repressible Operon

normally on but can be inhibited; produced when regulatory gene is inactive

inducible operon (2)

normally off but can be activated; used to produce more energy

high glucose; any lactose (lac operon)

cAMP is low which limits CAP which prevents transcription to breakdown lactose

low glucose; high lactose (lac operon)

more cAMP is produced which binds to CAP which binds to promotor to enhance transcription to break down lactose to make more glucose

Trp Operon

production of amino acid in bacteria

negative feedback loop with trp operons

When tryptophan levels are high, the repressor binds to the operator and shuts off transcription