iSCI 1A24 - cell structure and function

what is spontaneous generation hypothesis?

non-living materials can continuously give rise to living organisms?

what is miasma in relation to the spontaneous generation hypothesis?

noxious air spontaneously produced by decaying carcasses, rotting food, etc.

what was the conclusion come to based on miasma?

garbage and sewage turned into rats and caused miasma responsible for the plague

what are other examples supporting the spontaneous generation hypothesis?

spoilt moldy grains turn into mice, rotting meats turn into maggots/flies

what was the set-up of the original experiment disproving spontaneous generation hypothesis?

meat placed in an open container, a cork-sealed container, and a gauze covered container

what were the results of the original experiment disproving SGH?

open container had formation of maggots in meat; cork sealed container had no formation of maggots in meat; gauze-covered container had maggots on the gauze, but none in the meat

who created the original experiment disproving SGH?

Francisco Ready

what was the set-up of the final experiment disproving SGH?

two swan-neck flasks, one unbroken and one with the neck broken off, were filled with broth and boiled (to kill any microorganisms)

what were the results of the final experiment disproving SGH?

the curve of the unbroken flask prevented outside air from entering flask, so no contamination occurs; broken flask allows bacteria to reach the broth, so organism growth occurs

who created the final experiment disproving SGH?

Louis Pasteur

who discovered the cell?

Robert Hooke (1665)

who stated the existence of animalcules?

Antoni van Leeuwenhoek

what is the importance of cell theory, function, and structure

cells are building blocks of life, understanding root causes of disease, determining how to classify organisms as living

Who stated that all plants are made of cells?

Matthias J. Schleiden

what points did Schleiden make?

all plant tissues are made of cells; the embryonic plant grows from a single cell

who stated that all animals are made of cells?

Theodor Schwann

what points did Schwann make?

all animal tissues are made of cells; "all living things are composed of cells and cell products"

who was the first person to say that all cells came from pre-existing cells?

Robert Remak

who is credited as saying all cells came from pre-existing cells?

Rudolph Virchow

what are the three tenets of cell theory?

1) all living things are made of cells

2) cells are the basic units of structure and function in living things

3) all cells come from pre-existing cells through cell division

what is evidence proving cell theory?

microscopic observations

what is a cell?

a highly organized membrane-bound compartment capable of independent reproduction

is a virus alive?

no! it is not a cell also

what 4 features are shared among all cells (i.e. both prokaryotes and eukaryotes)?

cell membrane, ribosomes, cytoplasm, and DNA

what is the relative size of prokaryotes compared to eukaryotes?

prokaryotes (0.1-5um) are much smaller that eukaryotes (10-100um)

what are the implication of differences in cell size?

surface area-to-volume ratio is related to cell function

what is the significance of prokaryotes being smaller?

they have a larger SA:V ratio allowing for faster diffusion = faster metabolic rate = increased rate of growth/reproduction

what can be said about the limit of cell size?

it is based on the surface area-to-volume ratio

what can cause cell death?

when metabolic rate exceeds the rate of material exchange

what happens when a cell becomes too big?

it undergoes cell division

what is the benefit of multicellularity?

allows for an increase in size while maintaining a high SA:V ratio (i.e. metabolic efficiency)

what is an example of a maximization of SA?

villi and microvilli in the gut

villi

folds in the intestinal mucosa (tissue) which allow us to absorb nutrients at the highest possible rate

microvilli

similar to villi; microscopic folds in the plasma membrane of nutrient absorbing cells

what is the key difference between prokaryotes and eukaryotes?

eukaryotes have membrane-bound organelles

how many ATP are produced in one cycle?

38 ATP

what are subcellular organelles?

structures within eukaryotic cells that perform specialized functions

mitochondria

Powerhouse of the cell, site of ATP (energy) production

rough endoplasmic reticulum

primary site of protein synthesis; spotted with ribosomes

smooth endoplasmic reticulum

creates lipids and steroids

nucleus

control centre of the cell enclosed by a double membrane (nuclear envelope); the part of the cell containing DNA and RNA and responsible for growth and reproduction

chromatin

DNA + protein (coiled), anchored to a network of intermediate filaments (i.e. nuclear lamina)

nucleolus

subnuclear structure containing chromosome regions that encode for ribosomal RNA

gogli apparatus

modifies, sorts, packages and ships out proteins to where they are needed

Golgi vesicle

full of enzymes (and proteins) like hydrolase

lysosome

cell organelle filled with enzymes (from fusing with Gogli vesicle) needed to break down certain materials (macromolecules) in the cell

vacuole

helps sequester waste product

peroxisome

centres for oxidation reaction (detoxification) containing oxidative enzymes (e.g. catalase)

how is ethanol oxidized?

CAT oxidation of ethanol into acetaldehyde

where are the ethanol oxidation pathways?

minor in liver, major in brain

what are examples of key liver functions?

producing bile; removing drugs, chemical, and toxins for the body and neutralizing them

what might be formed as a byproduct of the neutralization of toxins in the liver?

free radicals, H2O2

what damage can be caused by free radicals?

damage to DNA

what fights against free radicals?

antioxidants

why would different cell types have different amounts of organelles?

different cells have different specializations

which organelles would liver cells have more of and why?

peroxisomes - liver is used for detoxification, which is what peroxisomes do

which organelles would muscle cells have more of and why?

mitochondria - muscle cells are always contracting and need energy (ATP) therefore need more mitochondria

what is the E145K mutation?

a point mutation in the Lamin A protein seen in patients with Hutchinson-Gilford Progeria Syndrome (HGPS) causing lobulated nuclei

what are the clinical features of HGPS?

premature ageing; atherosclerosis; death around 13 y/o, often from coronary disease/stroke