Biology Ch. 9-11 (Feely)

prometaphase

Nuclear envelope fragments into vesicles (gone), Mitotic spindle is completely formed, *Microtubules find kinetochores & attach to them*, Microtubules begin to direct chromosomes toward equatorial plane (midplane)

asexual reproduction

ONE parent produces offspring by dividing in two or producing egg that develops unfertilized into a CLONE, *Offspring are identical to parent* ex: Binary fission in bacteria/Mitosis in single-celled eukaryotes

homologue

One member of a homologous pair of chromosomes

interphase

PREPARATION for cell division: g1- first gap, most variable stage (could be absent or last days), cell *doubles in size,* performs normal metabolic func. s- *synthesis,* DNA REPLICATION, all 46 chromosomes duplicated, DNA still in CHROMATIN form g2- 2nd gap, final prep bf mitosis, continues to grow & make proteins in prep for dividing

anaphase 2

Sister chromatids are pulled apart to opposite ends of cell (Now each chromatid is called a chromosome)

interkinesis

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

DNA

(deoxyribonucleic acid) - nucleic acid that contains the genetic material of living organisms, Instructions for growth/function/response to stimuli, Passed on at level of cell (mitosis) and organism (meiosis), stretched out it would be 6 ft long

binary fission

*PROKARYOTIC cell division* ASEXUAL, New CIRCULAR DNA molecule copied from old, Daughter DNA molecules separate to opposite ends of cell, Cell begins to split down middle, Cell completes split into 2 cells each with identical DNA

genotype

*genetic makeup* of an individual, combination of alleles that code for a specific trait, Represent the allele combinations that result after gametes combine through reproduction, *code for phenotypes*

phenotype

*physical appearance* of organism (ex: brown fur/purple flowers), genes interact w/ environment to shape this, env conditions can cause genes to get turned off/on to display diff ones

punnett square

1. Identify the possible gametes each parent could produce(each gamete can only contain one allele for each trait) 2. Put the alleles (gametes) of one parent to the left of the square & the alleles of the other parent at the top 3. To determine the potential offspring, combine the alleles from each side and place the genotype in the corresponding box.

telophase

2 daughter nuclei form, Daughter chromosomes arrive at poles & *decondense back to chromatin*, Mitotic spindle degrades, Cytokinesis finishes up

diploid

2 sets of chromosomes, pairs of alleles on *homologous chromosomes* (2 possible variants)

tetrad

4 chromatids with 2 centromeres

humans

46 chromosomes, 23 (homologous) pairs

character

A heritable feature that varies among individuals (ex: eye color)

centrosome

A structure in animal cells containing centrioles (ANIMAL CELL) from which the spindle fibers develop.

cytokinesis 2

After meiosis of one diploid cell, the finished produce is *4 haploid cells (1/2 the number of chromosomes as original cell)* Males - 4 male gametes (sex cells) Female - 1 female gamete & 3 polar bodies

centromere

Area where the chromatids of a chromosome are attached

prophase

Chromatin completely condense into chromosomes NOW VISIBLE, Each chromosome is composed of identical sister chromatids joined at a centromere, right now a human cell would have 46 chromosomes composed of 92 chromatids, *nuclear envelope disassembles, animal cells: mitotic spindle forms from centrosomes w/centrioles at move toward poles of cell

telophase 1

Chromosomes (still composed of sister chromatids) reach the poles, Nuclear envelope begins to reform, Chromosomes begin to decondense, meiotic spindle disappears, Cytokinesis occurs- *NOW 2 HAPLOID CELLS*

prophase 1

Chromosomes condense, Nuclear envelope disappears, Spindle fibers form, *Homologous chromosomes pair up to form tetrads* CROSSING OVER occurs, microtubules from 1 pole attach to kinetochores of one homologue

prophase 2

Chromosomes condense, spindles form in each new cell, nuclear envelope begins to disappear again, no replication

metaphase

Chromosomes line up along midplane (to ensure genetic info split evenly) in a single file line (guided to middle by kinetochore microtubules), Polar microtubules overlap at midplane, Chromosomes are in the densest state!

metaphase 2

Chromosomes line up on metaphase plate in a single file line, NOT paired up with their homologue (alr split)

telophase 2

Chromosomes reach poles of cell, Chromosomes begin to decondense, Nuclear envelope begins to reform around each new nucleus *NOTE: Each new nucleus still has ½ the number of chromosomes as the original diploid cell (only one chromosome from each homologous pair)

homologous chromosomes

Chromosomes that have the carry genetic info of same sequence of genes and, one chromosome in pair maternal & other chromosome in pair paternal

meiosis

DIPLOID nucleus division in GERM cells (NOT somatic cells) to produce *4 genetically different nuclei,* Men - occurs in testes, Women - occurs in ovaries, produces HAPLOID egg/sperm cells (each w 1 set of chromosomes), interphase -> M1-> M2-> cytokinesis

nucleosome

DNA wrapped around 8 histone proteins

cytokinesis

Division of cytoplasm to form 2 daughter cells, Animal cell - formation of cleavage furrow, Plant cell - formation of cell plate

dominantly inherited disorders

Dominant alleles that cause a lethal disease are rare and often cause the death of affected individuals before they can mature and reproduce (ex: huntington's disease- degenerative disease of the nervous system caused by a lethal dominant allele with no obvious phenotype apparent until the individual is about 35-45 years old)

1st filial generation

F1, first generation of offspring

2nd filial generation

F2, second generation of offspring

Gregor Mendel

Father of genetics, bred pea plants, 3 decades after his death his research was found which set foundation for current genetic understanding

multifactorial disorders

Many diseases, such as heart disease, diabetes, cancer, alcoholism, and mental illnesses have both genetic and environmental components, Lifestyle has a tremendous effect on phenotype for cardiovascular health and other characters

anaphase 1

Microtubules separate the homologous chromosomes (tetrads separate)*NOTE: Sister CHROMATIDS of each chromosome are STILL ATTACHED at centromere, reduction division

metaphase 1

TETRADS (held together at chiasmata) line up along midplane, microtubules from other pole attach to kinetochores of the other homologue

monohybrid cross

a cross between two individuals that examines one character/trait (ex: flower color which= character)

dihybrid cross

a cross that examines TWO characters/traits at different loci, must find potential gametes

genome

all of the DNA in an organism Or all DNA in an organelle (ex: nDNA)

Interphase 1

all processes same as other, g1- normal metabolic func./doubles in size, s- dna replication, g2- finish cell growth & prep for division

allele

alternative form of a gene (ex: A= purple flowers, a= white flower)

dominant alleles

always expressed when present, Masks other alleles (capital letter)

cell divison

basis for continuity of life: Reproduction, Growth & repair, Production of sex cells, Cells come from preexisting cells

somatic cells

body cells (NOT reproductive), *mitosis*

karyotype

chromosome inventory, pictures captured by scientists during metaphase

genetic variation

created via meiosis: 1. crossing over (prophase 1), 2. random/independent assortment: in metaphase 1 orientation of tetrads RANDOM

test cross

determine the genotype of dominant phenotype by crossing with homozygous recessive

reduction division

diploid-> haploid

mitosis

division of a cell's DIPLOID *nucleus* to produce two new daughter nuclei that are genetically IDENTICAL to the original DIPLOID nucleus (PPMAT)

chromosome

dna packaged into linear molecules when READY FOR DIVISION, very tightly wound chromatin, scaffolding proteins help maintain structure, # varies among species (does not indicate complexity), moving form DNA is not accessible

recessive alleles

do not produce an effect when present with a dominant allele, Only expressed if NOT paired with a dominant allele (lowercase, must come in pair to be expressed, ex: rr)

crossing over

during PROPHASE 1 of MEIOSIS, homologous chromosomes exchange genetic information at chiasmata regions

reginald punnett

early professor of genetics, punnett square method to predict genotypes of offspring

fertilization

egg + sperm= diploid

zygote

fertilized egg, 1 set of chromosomes from each parent (diploid), produces somatic cells by mitosis & develops into adult

cell cycle control system

g1 checkpoint, g2 check point, m checkpoint

locus

gene location on a chromosome

sexual reproduction

genetic material from TWO parents is MIXED to produce *unique offspring,* Union of two sex cells (GAMETES) to form a single cell (zygote), Offspring are NOT genetically identical to parents, *Increases genetic variation*

heterozygous

having a pair of different alleles (Bb) expresses dominant phenotype

carriers

heterozygous individuals who carry the recessive allele but are phenotypically normal

chromatin

nucleosomes wound tightly together, mostly see DNA in this form, more accessible to read/build than chromosomes

ploidy

number of chromosomes in a cell (haploid 1 set/diploid 2 set homologous/triploid 3 sets)

multiple alleles

often *within a population* (NOT an individual) more than two alleles can exist for a single gene (ex: blood type- A/B/O)

epistasis

one gene masks the expression of another, so more than one gene affects a single phenotype, *BOTH RECESSIVE* (ex: aabb results in albino snake)

law of independent assortment

other principle of heredity developed by MENDEL: alleles for one gene segregate from one another independently of alleles for a different gene, Occurs during Metaphase I (diff genes line up differently which randomizes offspring, increasing genetic variation)

parental generation

p generation, initial cross of genetic study

homozygous

pair of IDENTICAL alleles (dom= BB, rec= bb), *true breeding*

law of segregation

principle of heredity developed by MENDEL: the two alleles for a gene separate when gametes are formed (homologous chromosomes) ex: meiosis 1, only 1 allele from each parent goes to offspring

phenotype ratio

ratio of dominant to recessive

genotypic ratio

ratio of homozygous dominant to heterozygous to homozygous recessive (HOD:HET:HOR)

gene

segment of DNA/unit of hereditary info that codes for a protein AND TRAIT, Provides information for cell function, about 20,000, inside of chromosomes, makes cell complex (not # of chromosomes), instructions to make proteins for diff functions

gametes

sex cells, haploid

recessively inherited disorders

show up only in individuals homozygous for the allele

anaphase

sister chromatids separate at centromere & are pulled by kinetochore microtubules to opposite poles of cell (now individual chromosomes), polar microtubules elongate which pushes poles further apart

centriole

structure in an *animal cell* that helps to organize cell division

genetic recombination

the exchange of genetic material between homologous chromosomes (pro 1), chromosomes now recombinants of parental types, happens in several places along each chromosome

genetics

the science of heredity, how genes vary

heredity

transmission of genetic information from parent to offspring

homozygous dominant

two dominant alleles (BB) expresses dominant phenotype

homozygous recessive

two recessive alleles (bb) expresses recessive phenotype

trait

variant for a character (ex: BROWN eyes)

incomplete dominance

when heterozygote has a phenotype that is intermediate between the 2 homozygotes (complete= classic inheritance), express MIXTURE of BOTH dom. & rec., result= new phenotype w/ blend of dom/rec (ex: red flower bred w white flower- offspring= red, white, & PINK)

polygenic inheritance

when multiple genes have an additive effect on one phenotype, Most of the really variable human phenotypes (height, weight, skin, hair, eyes), As many as 60 genes account for skin pigment!

pleiotropy

when one gene has multiple effects• Ex: cystic fibrosis - the recessive allele that codes for a defective chloride transmembrane protein (which causes multiple effects such as clogged blood vessels/liver & pancreas trouble/salty sweat, by only 1 gene)

codominance

when the heterozygote expressed both phenotypes at the same time equally (NOT an intermediate of the two) ex: brown and white spotted cow (both phenotypes DISTINGUISHABLE)