ANSC 224 - final exam

two steps of cell proliferation

DNA replication, cell division

define protein degradation

removes structural proteins

define cell differentiation

acquire specialized structure and functions

another name for tissue remodeling, cell turnover

cell apoptosis

2 characteristics of G1 phase

commitment to proliferate, period of cell growth

characteristic of S phase

DNA content/chromosomes double

two characteristics of G2 phase

check DNA integrity, prepare to divide

which three combined phases are known as interphase

G1, S, G2

define M phase

mitosis=nuclear division. chromosomes split and then nucleus cleaves to form two cells

during compensatory growth, increased food intake and appetite is primary driver of increased growth

true

compensatory growth is less likely if growth restriction occurs early in life

true

a 10% reduction in ___ will ____ efficiency of growth

lipid, increase

increasing body fat alters efficiency both positively and negatively. what are two examples of this

energy required to make a pound of adipose tissue is much higher than other tissues. energy declines as animals get fatter because there is no metabolism occurring in adipose lipid

why does fast growth improve efficiency

daily maintenance cost is lower per unit of weight gain

basal metabolism is determined in a ____ state, while _____ metabolism is determined when food intake equals heat production

fasting, maintenance

seasonal variation in body weight is the result of _____ during long day photoperiods

leptin resistance

how does leptin affect growth hormone

acts on hypothalamus to increase growth hormone secretion

hypertrophy vs. hyperplasia

hypertrophy is the increase of cell size, hyperplasia is the increase in cell number

2 important intracellular signaling pathways

MAPK, PI-3K

two important outcomes of MAPK, PI-3K signaling

altered gene expression to cause cell cycle. altered metabolism & protein synthesis

define each type of cell division (wild type, increase in cyclinE, increase in PI3K, increase in MAPK

wild type=4 cells turn into 8 cells of same size. cyclinE=cells decrease in size with each division. PI3K=4 cells turn into 8 bigger cells. MAPK=cells divide to make more cells of same size than normal

4 facts about epigenetic change in DNA

heritable change in gene expression, not a change in DNA sequence, caused by environmental events, methylation of DNA

during proteasome mediated degredation, ______ determines specific proteins targeted for degradation and performs poly-ubiquitination

E3 ligase

housekeeping genes

encode proteins essential for structure and metabolism

externally regulated genes

activated rapidly through intracellular signaling pathways

inducible genes

require translation of transcription factors to activate

epigenetically repressed genes

methylated/covalently modified DNA

molecules responsible for cell-cell and cell-matrix adhesion

cadherins and integrins

four facts about epigenetic modifications of DNA

happen over a long period of time, inherited, NOT a change in sequence, hard to undo

two characteristics of epithelial cells

high level of cell-cell adhesion, apical-basal polarity

compensatory growth

"catch-up growth" is accelerated growth of an organism following a period of slowed development

phenotypic differences in twin calves results from differences in _____ during development

epigenetic processes

_____ is the tissue with greatest relative growth from birth to maturity

skeletal muscle

during fetal development, tissues grow in size by _____

hyperplasia

PI3K occurs to regulate _____

cell size

mTOR is a precursor in the ____ pathway

PI3K

If you increase _____ the cell goes through the cell cycle faster, thus creating ____ cells

cyclin E, smaller

increasing PI3K increases protein synthesis causing cells to become ____ and necrotic because they cannot get enough ____

larger than normal, oxygen

mTOR integrates _____ with growth factor signaling

nutrient availability

since Rb inhibits transcription of cyclins in MAPK, a mutation in Rb protein would cause _____

excess cell proliferation

four types of cell signaling

autocrine, paracrine, endocrine, juxtacrine

epithelium vs. mesenchyme (4 facts of each)

epithelium=forms tightly joined structures, layered, cell-cell adhesions, cadherin rich

Mesenchyme-forms looser structure, cell-matrix adhesion, integrin rich

example of epigenetic change in genome

methylation of DNA and histone proteins

what does establishing embryo axes begin with

induction of primitive streak

interaction between ___ and ____ forms primitive streak

endoderm and ectoderm

primitive streak forms the ____ and then becomes the ____

neural tube, spine/spinal cord

gastrulation

embryonic mesoderm formation

embryonic mesoderm arises from _____

primitive streak formation

four things important in regulation of axial development

retinoic acid, fibroblast, growth factor, hox genes

hox genes are important for _____ of vertebrae, limbs, bones and genetalia

positional identity

what happens when a hox gene is deleted

the whole structure is deleted

____ formation results from segmentation

somite

somites are "blocks" of mesoderm that form in ___ and create _____ tissues

pairs

somites form ___ to ___

head to tail

neural tube forms ___ to ___

tail to head

if hox gene A9 and A10 are replaced by D11 and D12, what will be the result

all limbs will look like hind limbs

the connective tissue of limbs arises from proliferation of ____

lateral mesoderm

purpose of apical ectodermal ridge

regulates mesoderm proliferation in limb bud development

small animal breeds result form _____

IGF polymorphism

decrease in IGF activity _____ growth of almost all tissues

decreases

IGF stimulates what three things during growth of epiphyseal plate

chondrocyte and osteoblast proliferation, hypertrophy

formation of cranium and facial portions of skeleton result from _____

intramembranous ossification

endochondral vs intramemranous ossification

intra forms cranial/facial bones while endo forms long bones, vertebra, and ribs. (cartilage model forms first, then is converted to bone)

function of multinucleated osteoclasts

bone remodeling

multinucleated skeletal muscle fiber forms from fusion of ____

mononucleated myoblasts

muscle ____ becomes fixed near birth

number

major determinant of muscle contraction speed in adults

ratio of primary to secondary muscles formed in fetus

major determinant of muscle size in adults is the levels of ___ relative to ____

IGF relative to myostatin

major regulator of overall growth

IGF

extra ____ in young animals increases height but does not in adults due to _______

growth hormone, epiphyseal plate ossification

what type of tissue increases in size, number and decreases in insulin sensitivity from birth to 6 months of age

adipose tissue

three factors that control GH secretion

leptin, IGF, amino acids

increasing hormone receptor number results in a ____ response at the same _____

greater, concentration

3 things that mediate effect of GH on IGF activity

IGF binding proteins, IGF synthesis, and GH receptor numbers

most variable component during animal growth

adipose tissue

adipocytes have very slow turnover, even during ____

starvation

three things that impact adipocyte size

food intake, metabolism of fatty acids, spontaneous exercise

three things made and secreted by adipose cells

leptin, adiponectin, IGF-I

adipose participates in thermoregulation by ____ blood flow to white adipose

reducing

androgens and estrogens have an effect on hormone secretion, IGF production, and _____

metabolism

formula for determining metabolic weight

weight to the 2/3 power

steroid and ____ hormones regulate gene expression through _____

thyroid, ligand activated transcription factors

___ regulates body weight by ___ food intake and ____ adaptive thermogenesis

leptin, decreasing, increasing

four regulators of short term food intake

ghrelin, cholecytokinin, PPY, and glucagons

high leptin equals low _____

feed intake

increasing apidose tissue makes animals ____ because of the _____

less efficient, high energy content of tissue

why does fast growth make animals more efficicent

reduced energy requirements

what causes weight gain during pregnancy

induced leptin resistance

increased fetal cortisol causes a decrease in ___. this is the pathway to pregnancy

progesterone

adherent junctions are at _____

epithelial cell adhesions

ectoderm forms _____ which then forms which three things

outer epithelium, skin, hair, mammary glands

ectoderm forms ___ which then forms which two things

neural tube, brain and nerves

endoderm forms which 3 glands

thyroid, parathyroid, thymus

endoderm forms the __ which then forms which 3 organs

gut, forms liver, GI tract, pancreas

embryonic stem cells are ___ and can become ____

pluripotent, any cell type

muscle derived stem cells can only become ____ and form bone, muscle and ____

mesoderm, adipose

embryonic stem cells are found in the ____

blastocyst

three layers of embryonic germ cells

ectoderm, mesoderm, endoderm

when amount of stored fat reaches a certain level, ___ is secreted to activate receptors in brain

leptin, satiety hormone

which hormone is the opposite of leptin, and often referred to as the "hunger hormone"

ghrelin