Heredity

paracrine signaling

paracrine signaling

cells communicate with other local cells in vicinity

growth factors

local regulation in animals that simulate target cells to grow and divide and simultaneously receive and report

synaptic signaling

in animal nervous system; electric signal along nerve cell triggers secretion of chemical signal carrying neurotransmitters eventually triggering response in target cell

hormones

both plants and animals use this for long-distance signaling (also called endocrine signaling)

types of local cell communication/signaling

cell-cell: gap junctions (animal cells) and plasmodesmata (plant cells)

paracrine, synaptic

Stages of cell signaling

reception, transduction and response

reception

target cells detection of signaling molecule from outside cell; signaling molecule (ligand) binds to receptor

transduction

step or series of steps that converts signal to bring cellular response

signal transduction pathway

sequence of changes in series of different molecules (relay molecules)

response

cellular activity that is triggered

ligand

molecule that specifically bonds to another molecule; usually changes shape of receptor, initiating interactions

G-protein coupled receptor (GPCR)

cell-surface transmembrane receptor that works with help of G-protein

G-protein

protein that binds to energy rich GTP

ligand-gated ion channel

membrane receptor with a region that can act as a “gate” for ions opening or closing due to induced fit

intracellular proteins

in cytoplasm on nucleosol target cells and must pass through plasma membrane. ex steroids

transcription factors

control what genes are transcribed into mRNA in particular cell and time

protein kinase

enzyme that transfers phosphate groups from ATP to a protein; compose most of relay molecules on signal transduction pathway

phosphorylation cascade

pathway of signal transduction pathway containing protein kinases where signals are transmitted by

protein phosphatases

enzymes that can rapidly remove phosphate groups from proteins- dephosphorylation; make protein kinases available for use

second messengers

small; nonprotein, water soluble molecules or ions that can spread throughout through diffusion

cyclic AMP (cAMP)

epinephrine binds to G-protein activating enzyme that converts ATP to cAMP; important in mitosis-

cell division

reproduction of cells; allows multicellular eukaryotes to develop from single cell and replace dead cells

cell cycle

life of a cell from the time it first formed during division of parent cell until own division into two daughter cells

genome

cells genetic information

chromosomes

structures of packaged DNA; structure maintained by proteins called histones; nuclei in humans contain 46 chromosomes

chromatin

entire complex of DNA and proteins of chromosomes

somatic cells

body cells except reproductive

gamete cells

reproductive cells; XX-female, XY-male

sister chromatids

2 in duplicated chromosomes; joined copies of original chromosome; cohesions connect chromatids along length by protein complexes- sister chromatid cohesion

centromere

region made up of repetitive sequences in the chromosomal DNA where chromatid is attached most closely to sister chromatid; mediated by proteins

mitosis

division of genetic material in nucleus into 2 genetically identical diploid cells; 5 phases

cytokinesis

follows mitosis; division of cytoplasm; cleavage starts process; outside, contractile ring of actin microfilaments interact wit myosin and contract, pinching cell into 2 cells

miotic phase (M phase)

part of cell cycle that includes mitosis and cytokinesis and usually shortest part of the cycle

Interphase

longer stage that alternates with M phase; divided into G₁ phase, s phase and G₂ phase

5 stages of mitosis

prophase, prometaphase, metaphase, anaphase, telophase

prophase

chromatin fibers tightly coil; nucleoli disappear; each duplicated chromosome appears as 2 sister chromatids joined at centromeres, mitotic spindle begins to form centrosomes and microtubules; centrosomes move away from one another by lengthening microtubules

nucleoli

large structures in nucleus that are involved in synthesis of rRNA and ribosomes; disappear in prophase and reappear in telophase

prometaphase

nuclear envelope fragments; microtubules invade nuclear area; chromosomes become more condensed; kinetochores forms at each centromere of chromatid; microtubules attach to kinetochores; non-kinetochore microtubules lengthen cell with interactions

metaphase

longest stage; centrosomes at opposite ends of poles; chromosomes arrive at metaphase plate; kinetochores are attached to kinetochore microtubules of opposite plates.

anaphase

shortest stage; cohesion proteins are cleaves\d and each chromatid becomes independent chromosome; 2 new daughter chromosomes begin moving toward opposite ends as kinetochore microtubules shorten; cell elongates as non-kinetochore microtubules cohesion; both ends have equivalent and complete chromosomes

telophase

2 daughter cells in nuclei form in cell; nuclear envelopes arise from fragments of parent cells; nucleoli reappear; chromosomes become less condensed; microtubules are depolymerized

cleavage furrow

shallow groove in cell surface near old metaphase plate; oustide

cell plate

in plant cells, vesicles from Golgi move along microtubules to center where they release cell wall material so that cell plate enlarges until it fuses with plasma membrane

binary fission

prokaryotic reproduction in which cell grows to double its size and divides into two cells; DNA replicates and splits to opposite sides then cell divides.

growth factor

protein released by certain cells that stimulate other cells to divide

meiosis I and meiosis II

2 consecutive cell divisions resulting in 4 daughter cells with one set of parent cell chromosomes

allele

different version of gene at corresponding loci; variations in gene nucleotide sequence

prophase 1

2 members of homologous chromosomes associate along length; synapsis and crossing over occurs, and duplicated homologs pair up and crossover

metaphase 1

pairs of homologous chromosomes align at metaphase plate

chiasma

location where crossing over and swapping of genes occur; holds together homologous chromosomes into a tetrad

recombinant chromosomes

individual chromosomes that carry genes from different parents; increases genetic variability; result of crossing over

independent assortment chromosomes

at metaphase 1, homologous pairs are situated at metaphase plate and each pair may randomly orient with either maternal or paternal homolog closer to given pole

character

heritable feature that varies among individuals

trait

each varient for a character

true breeding

breeding over many generations of self-pollination

hybridization

mating, or crossing of 2 true-breeding varieties

P generation

true-breeding parents, parental generation

F₁ generation

hybrid offspring- first filial generation

F₂ generation

allowing F₁ hybrids to self-pollinate produces this -second filial generation

law of segregation

2 alleles for heritable character segregate during gamete formation and end up in different gametes

phenotype

appearance or observable trait and physiological

genotype

genetic makeup

testcross

breeding of an organism of unknown genotype with recessive homozygote; reveals genotype of organism

law of independent assortment

2 or more genes assort independently- each pair of alleles segregate independently of any other pair during gamete formation

multiplication rule

to determine probability of one event and other occurring, multiply probability of both events

addition rule

probability of any one of two or more mutually exclusive events will occur as calculated by adding individual properties

complete dominance

one allele shows up over another allele

incomplete dominance

neither allele is completely dominant; mix of phenotypes from parents; ex. pink flowers (from red/white)

codominance

2 alleles each affect phenotype in separate, distinguishable ways; ex. roan cow

Tay-Sach disease

inherited disorder in humans caused by recessive allele, brain cells in youth cannot metabolize lipids because of faulty enzyme and lipids accumulate, causing seizures, blindness, and degeneration of motor and mental performance; child dies within a few years

pleiotropy

genes that have multiple phenotypic effects; one gene affects lots of outcomes

epistasis

one gene affects phenotype of another because 2 gene products interact; phenotypic expression of gene at one locus alters that of gene at second locus; ex. labs

polygenic inheritance

additive effect of two or more genes on a single phenotypic character; many genes that affect one trait

multifactorial

many factors, both genetic and environmental that influence phenotypes

pedigree

family tree describing traits of parents and children across generations

carrier

seemingly phenotypically normal, heterozygotes that transmit recessive allele to offspring

cystic fibrosis

most common lethal genetic disease in U.S. due to recessive alleles; abnormally high concentrations of intracellular Cl, causing uptake of water making a mucus that builds up in the pancreas, digestive tract…; causes poor absorption of nutrients in intestines, chronic bronchitis, and recurrent bacterial infections

sickle cell disease

caused by substitution of single amino acid in hemoglobin protein of red blood cells; when O₂ content of blood is low, hemoglobin molecules aggregate into long rods, detaching red blood cells into sickle shape; can clump and clog blood vessels leading to physical weakness, pain, organ damage, and stroke and paralysis

Huntington’s disease

degenerative disease of nervous system caused by lethal dominant allele without phenotypic effect until 35-40 years old

density-dependent inhibition

phenomenon in which crowded cells stop dividing

anchorage dependence

to divide, cells must be attached to something; signaled to cell cycle control system via plasma proteins

transformation

process that causes cells to behave like cancer cells and cause ability to divide indefinitely

benign tumor

tumor that moves to or survives at another site; usually can be removed

malignant tumor

cells who's genetic and cellular changes enable them to spread to new tissues and impair functions on one or more organs, cancerous tumor

metastasis

spread of cancer cells to locations distant from original site; requires chemotherapy

how does cancer develop?

cancer cells do not stop dividing when growth factors are depleted; they evade normal control that triggers apoptosis; forms tumor which is a clump of abnormal cells within normal tissues; it has a density sensing factor that cannot control growth in dense conditions; loses desmosomes

differences of mitosis and meiosis

mitosis: diploid and haploid cell division (somatic cells); DNA replicates during interphase, before mitosis; one division; 2 genetically identical diploid daughter cells to parent with equal number of chromosomes; asexual reproduction

meiosis; diploid cell division only (gametes); DNA replicates during interphase before meiosis I but not meiosis II; 2 divisions; synapsis occurs during prophase 1 with crossing over- chiasma holds pair of homologous chromosomes together with sister chromatid cohesion; 4 genetically different haploid daughter cells from parent and each other; sexual reproduction

chromosome theory of inheritance

Mendelian genes have specific loci along chromosomes, and it is the chromosomes that undergo segregations and independent assortment

wild type

phenotype for a character most commonly observed in natural populations; denoted as superscript

mutant phenotype

traits alternative to wild type and are dure to alleles assumed to have originated as mutations in wild type allele

sex-linked gene

gene associated on either sex chromosome

X-linked genes

most genes; genes that X chromosome contains

Duchenne muscular dystrophy

progressive weakening of muscles and loss of coordination; life expectancy is around 20; absence of key muscle protein which is on X chromosome locus

hemophilia

X-linked recessive disorder; absence of 1 or more proteins required for blood clotting; excessive bleeding from injury due to slow forming blood clot; treatable with protein injections

Barr body

inactive X in each cell of female condensed into compact object; only one X chromosome can be activated, so those with 2 X chromosomes only express one because the other is inactivated

nondisjunction

members of pair of homologous chromosomes do not move apart properly during meiosis I of sister chromatids fail to separate in meiosis II

aneuploidy

condition when either of aberrant gametes unites with normal one at fertilization and zygote has abnormal number of particular chromosomes

monosomic- aneuploid zygote with missing chromosome

trisomic- aneuploid with triple chromosome

polyploidy

organisms with more that 2 complete chromosome sets in all somatic cells

deletion

when chromosomal fragments is lost; missing certain genes

duplication

broken fragment that is reattached as extra segment to sister/Non sister chromatid