BILD 2 midterm #1 flashcards

What are the advantages of multicellularity?

parts of the organism can specialize, grow larger, good for defence, can control ones shape better → adapt to specialized circumstances, control internal environment better

What are the challenges of multicellularity?

grow from 1 to many cells, reproduce themselves, get nutrients to all of their cells, get oxygen to all of their cells, maintain and health and stable environment, have diff parts of the organism communicate, deal w internal and external threats

Whats the main challenge of multicellularity?

getting substances to all cells of an organism, crossing cell membrane to get inside. Removing waste

The east of things being able to get through the membrane into the center is captured by _____

Surface area to volume ratio

math tells us that as shape gets bigger, volume gets ___

larger much more quickly thank surface area

What are the two ways to get around SA: V issue?

1. be made of many small units

2. be a different shape

Whats a no feedback loop?

change in x causes effects on y, then z. BUT z doesnt effect x

Feedback loop:

x→y→z goes back to x

negative feedback loop

change in level of something causes an affect that counteracts that change. Good for stability

Positive feedback loop:

change in level of something causes an effect that increases that change. Amplifies an effect or push the organism into a new state

Can no feedback push an organism into a new state?

Yes

What’s homeostasis?

organisms regulating certain aspects of their internal environment so that it stays in a relatively steady state even when there are external or internal environment changes

why is homeostasis essential?

molecules and cells in your body generally work best in a stable, narrow chemical and physical environment

Set point

narrow range for value of variable

control center

receives info from sensor and relays info to effector

effector

cells, tissues, and organs that change things to get back to the set point

regulated variable

the thing that is being controlled

sensor

things in tissue or organs the body detects changes

is heart rate regulated homeostatically?

No, theres no set point

is body temp regulated homeostatically?

yes

a _____ surface area to volume ratio keeps heat in

lower

why do penguins huddle?

there’s less SA, so they lose heat slower

organisms generate heat as a byproduct of what?

metabolism. Every cell does it as they do cellular respiration

How is heat lost?

through skin and other external surfaces

to exchange stuff w environment we want

high sa:v

to not exchange stuff w environment we want

low sa:v

endothermy

organisms that regulate their body temp to remain constant

ecothermic

organisms that cant regulate their body temps

what is humans set point for body temp?

37 degrees Celsius

What does your body do to cool?

sweat and vasodilation

sweating

stimulation of sweat glands, liquid sweat evaporates from heat on skin. Skin loses heat so cools down

vasodilation

capillaries underneath skin fill w/ blood to bring closer to surgance of skin, so can loose heat easier

How does the body warm

shivering and vasoconstriction

vasoconstriction

capillaries underneath skin get constricted (shut off) to take blood away from surface of the skin, so less heat is lost

Fever is an example of?

regulating the set point. NOT a positive feedback loop

what makes cells different?

their proteins

Pluripotent Cell (zygote)

cells from any of the three germ layers, early embryo, ex: ESC, iPS

Stem Cells

a limited range of cell types, found in many tissues, ex: hemotopietic, neural, mesechymal stem cells

fully differentiated cells

do not divide, in all tissues, ex: neurons, skin cells, lung cells

are most cells in your body pluripotent?

No, your body’s cells are determined and differentiated, committed to expressing one fate

What is determination?

cell committed to particular fate, occurs through changes in gene expression that are not yet visible exteriorly, occurs before differentiation

What differentation?

cell becomes specialized in form and function to a particular fate, also involves gene expression of genes that are specific to that cell type, occurs after determination

Fertilization

process of fusion or union of the sperm w/ mature ovum. Producing fertilized zygote

Cleavage

early cell division occurs w/o any overall growth. results in each cell being ½ as large of the parent cell

morula

solid mass, no overall growth. Just cleavage

blastocyst

cells on the outside of the morula flatten out and the inside develops into a hallow ball (cleavage ends)

inner cell mass

will develop into the fetus ES cells derived from ICM

are cells are determined can they split up and become 3 germ layers?

No, and no differentation

whats the growth pattern of a zygote?

fertilization → cleavage → morula → cleavage → blastocyst → gastrulation → organogensis → 9 wk, human fetus → growth → baby

Ectoderm

outer layer. gives rise to outer layer of skin (epidermis), nervous system

mesoderm

middle layer. gives rise to skeletal system and muscle, circulatory system and lungs, excretory and reproductive systems

endotherm

inner layer. gives rise to lining of digestive tract and digestive organs, some glands live liver pancreas and thyroid, lining of respiratory reproductive and excretory tracts

What happens sometimes during cell division?

determinants inside the parent cell are split unequally, so the daughter cells inherit different

what happens most of the time during cell division?

induction- some cells of the embryo send signals to cause other cells to differntiate into various things. signals can be secreted chemical or proteins on the sutrface of the cell

what two things can cause either determination or differentiation to occur?

induction and parent cell are split unequally

whats cancer

disease of uncontrolled cell division, caused by mutations/alterations in DNA. has mutations in genes that affect mitosis and spreading

tumor suppressor

gene normally blocks cell growth and mitosis. inactivating promotes cancer ex: p53

proto-oncogenes

encourage growth will promote cancer when activated

dna repair genes

normally fix error fix errors in DNA, so will promote mutations and therefore cancer when activate

what are benign tumors

slow growing, non invasive, more differentiated (looks like normal cells), not considered cancerous

what are maligant tumors?

uncontrolled growth, invasive (pushes into other tissue), undifferentiated, cancerous

Why do tumors need a blood supply to grow larger than a few mm in diameter?

needs to increase its SA

angiogensis

growth of new blood vessels. positive feedback loop (more blood vessels = bigger tumor = need more blood vessels)

a small tumor can get all its nutriets through

its surface area

what are the similarities between cancer and development?

rapidly dividing cells, generally look and behave like immature, many cells moving around, cells arent differentiated or doing mature functions

why are cancer and development similar?

many cancer reactivate gene expression patterns seen only during development

menthotrexate

blocks the effects of folate/folic acid, which is essentail for synthesizing dna and rna (rapidly dividning cells in cancer need folate, but so do reg cells and cells during development)

radiation and chemotherapy

killing dividing cells ex: menthotrexate

surgery

cut out the tumor

immunotherapy

enhances the ability of your immune system to kill cancerous cells

what are the two methods of lond distance communication within animal bodies?

endocrine system using hormones and nervous system using nuerons

hormone

a signaling molecule that is produced in low concentrations by one part of an organisms body and transported to other parts where it binds to a specific receptor and triggers response in target cells and tissues

endocrine

signals are transported through blood, target cells throughout body, reaches target cells more slowly, effects tend to last longer

nervous system

signals are electrical or chemicals carried through extracellular fluid, targets neurons muscles and some glands only, reaches target cells more quickly, effects tend to last a shorter amount of time

auxin

one of many plant hormones, responsible for bending towards light (phototropism). made at low concentrations in the tip, travels to the dark side of the stem binds to a receptor there and causes bending

auxin and animal hormone similarities

molecules travel in fluid, enable longer distance communication, have a variety of effects on diff tissue types

what hormones are related to the reproductive system

estrogen, progestrone, GnRh, LH, FSH, etc

what hormones are related to the digestive system

insulin, glucagon, ghrelin, leptin

what hormones are renal hormones

ADH, renin, angiotensin II, aldosterone

only specific hormonees affect specific tissues or cells bc all target cells____

have receptors for the hormone

what happens when a cell recieves a hormonal signal?

it uses a receptor to detect the hormone, the receptor starts a signal transduction cascade inside the cell, the signaling cascade causes the cell to make some sort of response

various molecular pathways inside the cell (signal transduction pathways) can be activated to cause:

activation of certain enzymes, release of calcium or other ions, gene expression (making proteins)

what are the two ways for having different effects on different target cells?

1. diff target cells may have diff receptors for the hormone

2. diff target cells use the same receptor but diff signal transduction pathways inside the cells to turn the receptors response into a cellular response

What are the two closes of hormones

amino acid based and steroid based

amino acid based hormones

generally soluble in water, derivatives of single amino acids, polypeptides

steriod based hormones

solid in lipids, cholesterol based

water soluble hormones

easily travel by itself through blood, cant pass through cell membrane, receptor is on the membrane of the cell. have various cellular responses

lipid soluble hormones

needs transport protein to move through blood, pass easily through cell membranes, receptor is within the cytoplasm or nucleus of the cell. leads to gene expression creation of new proteins

hypothalamus

receives info fro, the rest of the brain and initatiates responses by secreting hormones

pituatary

receives signals from the hypothalamus and secretes diff hormones

pituitary hormones

often target endocrine glands to make them secrete more hormones

pathway for hypothalamus

hypothalamus →(GhRH) → anterior pituitary→ (GH) → liver (ig f-1)

posterior pituitary

made of extension of neurons (axons) from the hypothalamus where these neurons release some hormones

anterior pituitary

is a gland that makes and releases hormones in response to hypothalamic hormones

thyroid hormone

affects virtually every cell in body, increases how much energy you use at rest (basal metabolic rate) through stimulating cells to use oxygen and make ATP, promotes growth and developent

Thyroid hormone (thyroxine) contains and requires ____?

iodine, w/o → goiter thyroid gland swelling

a goiter forms when

lack of iodine builds up precursor molecules to thyroid hormone build up

what are the effects of lack of thyroid hormones?

adults: cold, lethargic, weight gain

kids: stunt growth, irreversible intellectual disability due to issues w/ brain development

hypertrophism

too much thyroid hormone

cortisol

promotes higher blood sugar levels by acting on liver and muscle, is a glucocorticoid hormone. depress function of the immune function. for chronic stress: disrupting skeletal, gastrointestinal, and neural function (including learning)