ANS 002 FINAL

myogenesis

changes in muscle cell development and formation of muscle tissue

hyperplasia

increase in number of cells—prenatal

hypertrophy

increase in size of cells—postnatal, addition of more proteins

How much of an animals body mass is muscle?

30-40%

describe smooth muscle

unstraited, mononucleated, sustained contractions in the vascular system, reproductive system, and GI tract, involuntary, goes not contract rapidly

unstraited muscle

no distinct banding pattern

describe cardiac muscle

straited, responsible for contracting the heart, involuntary, functionally multinucleated, gap junctions allow for rapid coordination of contractions

Describe skeletal muscle

straited, multinucleated, responsible for movement, voluntary

myocyte

muscle cell or muscle fiber

myofibrils

functional unit of the muscle cell

sarcomere

building blocks of a myofibril

fasciuli

bundle of myocytes

describe the three sheaths in connective tissue

epimysium encases the entire muscle and the first layer, the perimysium encases the bundles of muscle fibers, and the endomysium encases the individual muscle fibers

sarcolemma

myocyte cell membrane, connects fiber to endomysium

sarcoplasm

cytoplasm of myocyte, stores glycogen for energy and myoglobin for red color and oxygen storage

transverse tubules (t-tubles)

communication channel into the interior of the muscle fiber

sarcoplasmic reticulum

stores Ca2+ in relaxed muscle

what are myofibrils composed of

myosin and actin

when myofibrils contract..

the muscle fiber contracts

when parallel muscle fibers contract

the entire muscle contracts

Striations

distinct, altering light and dark bands of myofibrils, myosin is the thick filament and actin is the thin filament

sarcomeres role in muscle contraction

sarcomeres shorten and the filaments slide across one another, bringing the z-lines closer together, the A-band stays constant, and the I-band shortens

Z-disc in sarcomere

boundary of a sarcomere, provides support

A-band in sarcomere

entire myosin, some actin

I-band in sarcomeres

only actin, split in two halves

H-zone in sarcomere

only myosin, no actin

Direct phosphorylation

short duration (short lasted energy), 1 creatine phosphate makes 1 ATP

anaerobic glycolysis

one glucose makes about 2 ATP, no oxygen and not a lot of energy

Oxidative phosphorylation

one glucose makes 38 ATP, long duration, needs oxygen

exsanguination

blood removal

what happens during the harvesting of meat

exsanguination, interrupts supply of oxygen to muscles, shifts from aerobic to anaeroebic pathways, oxidative phosphorylation no longer working because it need oxygen, recycling turns off—accumulation of lactic acid

pH of muscle

7.2

pH of meat

5.4-5.5

glycogen in muscle

represents 1% of muscle weight, reduced to 0.1% by PM glycolysis

PM glycolysis

no oxygen, produces lactic acid that accumulates in the muscle

what causes pH decline in muscle and how much does it decrease?

accumulation of H+ ions causes muscle pH to decline from 7.72 to 5.4-5.5

how much of muscle is water

75% water

Bound water

held tightly, can bind under extreme condition, 4-5% of water in muscle

immobilized water

held by weaker attractive forces, cell breaks down and water is lost easily, 80-90% of water in muscle

free water

held by capillary forces, lost very easily, theoretically theres no free water in live muscle

Water Holding Capacity (WHC)

the ability of meat to retain water during applications of external forces such as cutting, heating, grinding, or pressing

when is WHC the lowest?

when the pH nears the isoelectric point of muscle proteins

isoelectric point of muscle proteins

number of + and - charges are equal

What’s pale, soft, exudative (PSE) meat caused by?

rapid rate of pH decline and high muscle temperatures lead to excessive moisture lost, pH values less than 5.4

what is dark, firm, dry (DSE) meat caused by?

depletion of muscle glycogen (long-term stress), results in pH higher than 6.2

what happens in rigor mortis

creatine phosphate and glycogen are depleted, muscle slowly depletes ATP, permanent actomyosin cross-bridges are formed, loss of extensibility and muscle shortening, delay phase: still some energy, onset phase: stored energy depleted, completion phase: loss of extensibility

mammogenesis at puberty

ductal elongation promoted by estrogen, minimal alveolar development, progesterone present in spurts

lactogenesis

initiation of lactation when giving birth

galactopoiesis

maintenance of lactation, when offspring is suckling it stimulates mammary glands

involution

regression of pre-pregnant state, stimulus removed, mammary structure regresses

exocrine gland

range from skin surface milk patch (monotremes) to variable number of defined glands

alveoli

structures where specialized cells are arranged and where milk is synthesized

how is milk secreted

by a duct system

median suspensory ligament

makes sure udder attached to abdominal wall, if separated, will swing “penjulus udder” and more prone to infection and is uncomfortable

secretory tissue

part of interior structure of udder, contains mammary epithelial cells (MEC) and organized on three levels: alveolus, lobules, and lobes

alveolus

contains MEC found in a single layer lining the lumen, or central cavity, MEC do all the work, myoepithelial cells and capillary blood vessels surround each alveolus and contract in response to oxytocin

lobules

clusters of 150-200 alveoli, surrounded by fine membrane of connective tissue, drained by a common duct

lobes

groups of lobules, surrounded by thicker connective tissue, drained by a common duct

Mammary epithelial cells (MEC)

cells that make and secrete milk

estrogen role in mammary gland development

stimulates duct and cistern development, present during follicular phase of estrous cycle, lengthening and branching of ducts, epithelial components on the end

progesterone role in mammary gland developement

induces formation of alveoli, present in the luteal phase of the estrous cycle, causes duct cells to multiple, enlarge and/or widen, complete alveoli development when CL stays (gestation)

mammogenesis during pregnancy

ductal and alveolar growth, progesterone levels are maintained

chromosome

contained in the cell nucleus, composed of DNA and proteins (macromolecules)

gene

functional segment on chromosome that encode specific protein, only 2-3% of DNA actually encodes for protein

locus

site on a chromosome

allele

different versions of a gene, there can be many alleles for a locus in a population, but only two alleles at a locus in an individual

cell cycle (definition)

series of stages in a cell leading to its division

what are the phases of the cell cycle?

Gap 1, S phase, Gap 2, M phase—interphase is g1, s, g2 where the cell prepares for division

mitosis

produces two daughter cells with the same genetic content as their parent cells (2n)

meiosis

produces haploid gametes, single copy of each chromosome as a result, crossing over of paternal and maternal chromosomes occurs

co-dominance

when both alleles contribute equally to the phenotype (ex: red and white cow makes a cow with both red and white fur)

incomplete dominance

blending of dominant and recessive traits, can be the result of additive gene action (ex: red and white flowers make pink flowers)

over dominance

the phenotype of the heterozygote lies outside the phenotypic range of both homozygotes (ex: individuals heterozygous for sickle cell anemia have higher fitness with partial resistance than both homozygous)

epistasis

when the phenotype of one gene depends on or is modified by other gene(s) (ex: coat color in horses)

gene frequency

proportion of loci in a population that contain a particular allele

allele frequency

proportion of different alleles within a population

a locus is polymorphic if…

if allele frequency is less than 0.95

heterozygosity

number of heterozygotes in a population

hardy-weinbery equation

p² + 2pq + q² = 1

hardy-weinberg equilibrium assumptions

random mating, no genetic variance, no selection, no mutation, no migration, large population

gene editing tools

enable site-specific cuts in genome in efficient fashion, make a break in the genome at a precise location, cuts lead to small insertions and deletions (indels) leaving a mutation that will be knocked out. ‘knock-in’ adds sequence to genome

what are some ways biotechnology is used in agriculture

increased growth in salmon, more efficient at converting feed in body mass; decreased environmental pollution in pigs, phytase transgene in their saliva so they can digest phosphorus; decreased heat stress in cattle, gene editing of prolactin receptor produces slick cows

How can DNA be used for diagnostics?

performance/traits, parentage/genetic markers, we can detect the presence of pathogen or disease based on the DNA or RNA sequence,

recombinant DNA

making DNA molecules in the lab by joining species species together

estrous synchronization

use of progesterone to block LH and FSH in ruminants, inject prostoglandin during the luteal phase, induce estrus in pigs with PG 600

superovulation

artificially induced ovulation of more oocytes than is normal for that species, intramuscular injections of FSH for 3-4 days and PGF2a on the third day

embryo transfer

oocytes collected from ovaries collected after slaughter or by ovum pickup following superovulation, oocytes matured and fertilized in vitro, resulting embryos transferred or following culture