Bio Unit 2

Genetic Material

DNA is stable store of instructions; RNA allows instructions to be used

Cell theory

Every organism is made up of cells, the smallest organisms are single cells, all cells arise from preexisting cells.

Prokaryotic

Has a singular circular chromosome of DNA, nucleoid, plasmids

Nucleoid

location where you find the chromosome

Plasmids

small circles of DNA that can be passed between bacteria

Prokaryotic DNA is attached to…

the plasma membrane

Prokaryotic divides by

fission

Fission

DNA replicates, chromosomes pushed apart, new plasma membrane between them, cells divide into 2 daughter cells

eukaryotic

store genetic material in their nucleus, can be unicellular or multicellular, double membrane, chromosomes

DNA double helix is wound around

histone proteins

DNA and histones coil and wrap tightly to pack into

chromatin

Chromatin

condensed chromosomes

Karyotype

set of chromosomes from a eukaryotic cell

Homologous chromosomes

chromosomes that make an identical pair (diploid)

Sex chromosomes

x and y, determines biological sex

Autosomes

chromosomes that are not sex chromosomes

Centromere

temporary structure during cell division, keeps sister chromatids together, attachment site for microtubules

Telomere

protects ends of chromosomes

Stem cells

ability to divide, have potency

Potency

the ability to become almost any cell type

Somatic

all cells in your body except sperm and eggs

Somatic cells divide by

mitosis

Meiosis

cell division that produces gametes(sperm and eggs)

Asexual reproduction

reproduction from just one parent

Chromatid

one copy of the duplicated DNA

Eukaryotic cell cycle

G1, S, G2, M phase

Interphase

Period between cell division(G1, S, G2)

G1

1st growth phase, lasts for cell division until onset of chromosome replication, cell may differentiate and perform specialized functions

S phase

cell replicates DNA

G2

2nd growth phase, lasts from end of S phase until M phase

M phase(mitosis)

mitosis

Spindle fibers(mitosis)

microtubules, type of cytoskeletal protein

Prophase(mitosis)

chromosomes condense, spindle fibers form, nuclear envelope disappears, spindle fibers attach to the kinetochore(structure in centromere

Metaphase (mitosis)

Chromosomes line up at cell equator (spindle fibers push them there)

Anaphase (mitosis)

Spindle fibers shorten, pulling chromosomes towards the poles of the cell

Telophase( mitosis)

Spindle fibers disintegrate, nuclear envelope reforms around chromosomes

Cytokinesis (mitosis in animal and eukaryotic cells )

actin-myosin interaction results in 2 daughter cells

Actin-myosin interaction

myosin “walks” along actin, creating a cinch (cleavage furrow) to pinch the cell apart

Cytokinesis(plants)

vesicles in the Golgi apparatus bring membrane and cell wall components to middle of cell (vesicles fuse to form a cell plate)

G1 checkpoint

can only pass if cell size is adequate, nutrients are sufficient, social signals are present, DNA is undamaged

G2 checkpoint

can only pass if chromosomes have replicated successfully, DNA is undamaged, Activated MPF is present

M phase checkpoints

chromosomes have attached to spindle apparatus (Metaphase-Anaphase checkpoint), chromosomes have properly segregated and MPF is absent(Anaphase-Telophase checkpoint)

Cancerous cells have

2 type of defects

If DNA is physically damaged

p53 protein activates proteins that pause the cell cycle until damage repaired

If DNA damage isn’t repaired

cell death (apoptosis) is triggered, if the cell continues to divide it could lead to cancer

Cancer defects

ones that prevent tumor suppressor genes from shutting down cell cycle, ones that activate proteins required for cell growth when they should not be active

Benign cancer cells

may continue to divide but are not invasive (don’t spread from tumor)

Malignant tumors

divide and spread to adjacent tissues and distant tissues through lymphatic and blood vessels

Haploid

cells with one copy of a chromosome

Polypoid

cells with more than 2 copies of a chromosomes

Aneuploid

cells missing a copy of a chromosome(usually not viable)

Gametes fuse to form…

new organisms in sexual reproduction

Meiosis

halves the number of chromosomes

Humans have

23 pair of chromosomes

Meiosis consists of

2 cell divisions

Meiosis I

the 2 homologs of each chromosome pair separate into 2 haploid daughter cells

Meiosis II

the sister chromatids of each chromosome separate into 2 daughter cells, resulting in 4 haploid cells

Early Prophase I

Homologous pairs get together(synapsis), Chromosomes in synapsis(bivalent chromosomes)

Synapsis

homologous pairs together

bivalent Chromosomes

Chromosomes in synapsis

Late Prophase I

Homologous chromosomes cross over, chromosomes attach to spindle fibers

Chiasmata

Crossover points, physical breaking points where chromosomes swap adjacent segments of DNA

Recombinant

chromosomes resulting from crossover, has pieces of paternal and maternal chromosomes

metaphase I

Parring homologs line up at metaphase plate, random

Anaphase I

Homologues separate and move toward poles

Telophase I

chromosomes finish separating, following cytokinesis.

No chromosome replication occurs

between meiosis I and II

Prophase II

spindle apparatus forms and spindle fibers attach to each sister chromatid

Metaphase II

chromosomes line up at metaphase plate

Anaphase II

sister chromatids separate and move toward opposite poles

Telophase II

nuclear envelope forms around each set of haploid chromosomes; cytokinesis happens

Nondisjunction

when chromosomes don’t separate correctly during meiosis

Locus (loci pl.)

A gene located at a specific location on chromosomes

Alleles

different versions of the same gene

Homozygous

have 2 of the same allele

Heterozygous

have 2 different alleles for a gene

Phenotype

Individual’s observable features

Pure lines

produce offspring identical to themselves when self fertilized

Hybrids

mate 2 different pure lines together

Test Cross

Breed recessive homozygote to individual with unknown genotype

Dihybrid cross

mating between parents that are both heterozygous for two traits

What is the ratio of a dihybrid cross

9:3:3:1

Principle of Segregation

Pair of alleles are separated during meiosis I in the formation of gametes

Chromosome Theory of Inheritance

genes are discrete units located at specific sites(loci) on chromosomes

MPF

M phase promoting factor, has 2 distinct subunits; protein kinase and cyclin