bio exam 4

cross-fertilization

pollen from one plant placed on stigma on other plant

cross-fert is accomplished by

prying open immature flower and removing stamen, then take pollen from another flower’s stamen and place on stigma

P gen

true-breeding parents

F1 gen

offspring of P cross Monohybrids

F2 gen

self-fertilization, recessive trait appears

Mendel’s 3 important ideas

traits are dominant or recessive, genes and alleles (every person has 2 genes for a character and a gene has 2 variant forms), and segregation of alleles ( 2 copies of gene carried by F1 gen separate from each other so that each sperm or egg carries only one allele)

Mendel’s Law of Segregation

2 copies of a gene separate from each other during transmission from parent to offspring

alleles

alternate versions of a gene

genotype

genetic composition of individuals

phenotype

physical or behavioral characteristics that are results of gene expression

test cross is when you

breed dominant with recessive

chromosome theory of inheritance

1. chromosome contain genetic material (genes found in chromosomes)

2. chromosomes replicated and passed from parent to offspring

3. nucleus of a diploid cell contains 2 sets of chromosomes (homologous pairs)

4. at meiosis, 1 member of each chromosome pair segregates into each daughter nucleus

5. gametes are haploid cells that combine to form diploid cells during fertilization, with each gamete transmitting one set of chromosomes to the offspring

locus

physical location of a gene on a chromosome

law of independent assortment

applies to genes on chromosomes that are not homologous or far apart on same chromosome

linked genes

located closer together (gene) tend to be inherited together

disease genes can be

dominant or recessive, autosomal or sex-linked

mechanism for sex determination

X-Y, X-O, X-W

X-linked diseases/disorders

Hemophilia A, color blindness, DMD

complex forms of inheritance

codominance or incomplete dominance

incomplete domianance

show intermediate phenotype of parental variables, ex: red and white flower produce pink flower

codominance

2 alleles are expressed equally, ex: blood type AB

epistasis

gene at one locus alters phenotypic expression of gene at a 2nd locus, ex: Labrador retriever

pleiotropy

one gene has multiple phenotypic effects, responsible for multiple hereditary diseases, ex: CF and sickle cell anemia

budding

new individuals arise from outgrowths of existing ones

fragmentation/regeneration

breaking of body into pieces, some or all of which develop into adults

parthenogenesis

development of a new individual from an unfertilized egg; occurs in some verts

sexual reproduction

offspring form by fusion of a male gamete and female gamete to form zygote

asexual advantages and disadvantages

1. simple to reproduce many'

2. reproduce in isolation

3. rapid reproduction

4. stable environment needed with little selection pressure for diversity

sexual advantages and disadvantages

1. 2 individuals

2. greater variation due to genetic recombination

gametogenesis

production of gametes, gametes formed in gonads

spermatogenesis

development of sperm (1 cell becomes 4 gametes), continuous and prolific, gonads= testes

structure of sperm

head with acrosome (specialized vesicle containing enzymes that help penetrate an egg), midpiece, and tail

oogenesis

development of an ovum (1 cell=1gamete), prolonged process, gonads=ovaries

2 layers around the ova

1. zona pellucida → layer of glycoproteins

2. cumulus mas → layer of cells that protect and nourish oocyte

in spermatogenesis, the amount of genetic material and cytoplasm is

equal, all four products develop into sperm

in oogenesis, the amount of genetic material and cytoplasm is

not equal, only ¼ of meiosis becomes an egg

the production of sperm ______ _____ occur at the body temp of most mammals

does not

scrotum

a fold of the body wall that maintains testes temp at about 2 degrees C below body temp

sperm is produced in highly coiled tubes called

seminiferous tubules

leydig cells

secrete testosterone

stertoli cells

provide nutrients and protection to developing sperm

epididymis

coiled duct connects testis to vas deferens, where sperm complete maturation and become motile

pathway of sperm during ejaculation

1. sperm propelled through the muscular vas deferens

2. ejaculatory ducts

3. exits penis through urethra

semen

composed of sperm and secretions from accessory glands

external of female reproductive anatomy include

clitoris and 2 sets of labia

internal of female reproductive anatomy include

a pair of gonads (ovaries), a system of ducts, and chambers that carry gametes and house the embryo and fetus

support cells

nourish and protect oocytes during formation and development

gonadotropin is a

releasing hormone (GnRH) secreted by hypothalamus, directs release of FSH and LH

LH and FSH in male reproduction

by anterior pituitary, LH stimulated leydig cells, FSH binds sertoli cells= nourish sperm

Testosterone

by leydig cells in testes, stimulate spermatogenesis, promotes sexual and aggressive behavior

LH and FSH in female reproduction

affects follicle maturation, in anterior pituitary

estrogen and progesterone

in ovary, affects uterus lining

female phases

1. follicular- growth and differentiation of follicle

2. ovulation- follicle ruptures: releases egg, zona pellucida, and cumulus mass

3. luteal- corpus luteum develops and secretes progesterone

proliferative phase

endometrium becomes thicker and more vascularized

secretory phase

glands develop that secrete nutritive substances to sustain embryo for first 2 weeks

what hormone do pregnancy test look for

hCG → human chorionic gonadatropin

ectopic pregnancy

embryo implants in an abnormal spot

embryonic period

weeks 3 to 8

fetal period

9 weeks to birth

neurons

nerve cells that transfer info within body, 2 types: electrical and chemical

dendrites

highly branched extensions that receive signals from other neurons

axon

longer extension, transmits signals to other cells

axon hillock

cone-shaped base of an axon, where signals are generated

axon terminals

convey chemical or electrical message to other cells

synapse

junction between cells that axon transmits signals through

synaptic terminals

part of each axon branch that forms a synapse

neurotransmitters

chemical messengers that pass info from transmitting neuron to receiving cell

glial cells

nourish neurons, insulate axons of neurons and regulate fluid surrounding neurons

3 main types of neurons

1. sensory- detect info from outside world or internal body conditions and send to CNS

2. motor- send signals away from CNS to elicit response

3. interneurons- form interconnections between other neurons, integrate the sensory input