unit 2: cell structure & function

Subcellular components

Organelles

Any of several membrane enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells.* cells, cells they're made of organelles *

Ribosomes not an organelle

A complex of rRNA & protein molecules that functions as asite of protein synthesis in the cytoplasm ; consists of alarge & a small subunit. in eukaryotic cells, each subunit is assembled in the nucleolus

Ribosomal RNA ( rRNA )

RNA molecules that, together with proteins, make up ribosomes I this rRNA is the most abundant type of RNA.

mRNA or messenger RNA

Endoplasmic reticulum or E.R.

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane & composed of ribosome-studded ( rough) & ribosome-free ( smooth) regions.

Rough endoplasmic reticulum or rough E.R.

The portion of the endoplasmic reticulum with ribosomes attached .

Smooth endoplasmic reticulum or smooth E.R.

The portion of the endoplasmic reticulum that is free of ribosomes / no ribosomes attached

Golgi complex

An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, & route products of the endoplasmic reticulum & synthesize some products, notably non-cellulose carbohydrates

Mitochondria

An organelle in eukaryotic cells that serves as the site of cellular respiration : uses oxygen to breakdown organic molecules & synthesize ATP.

Lysosomes

A membrane enclosed sac of hydrolytic enzymes foundin the cytoplasm of animal cells & some protists

Hydrolytic enzymes

Vacuole

A membrane bounded vesicle whose specialized function varies in different kinds of cells.

Apoptosis

A type of programmed cell death, which is brought about by activation of enzymes that break down manychemical components in the cell.

Hypotonic

Referring to a solution, that when surrounding acell, will cause the cell to take up water.

Isotonic

Referring to a solution that, when surrounding a cell causes no net movement of water into or out of the cell.

Hypertonic

Referring to a solution that when surrounding a cell, will cause the cell to lose water.

Passive transport

The diffusion of a substance across a biological membrane with no expenditure of energy.

Active transport

The movement of a substance across a cell membrane against its concentration or electrochemical gradient mediated by specific transport of proteins & requiring an expenditure of energy.

Chloroplasts

An organelle found in plants I photosynthetic protists that absorbs sunlight & uses it to drive the synthesis of organic compounds from carbon dioxide & water

Turgor pressure

The force directed against a plant cell wall after the influx of water & the swelling of the cell due to osmosis

Thylakoids

A flattened, membranous sac inside a chloroplast. Thylakoids often existin stacks called grana that are interconnected I their membranes contain molecular machinery used to convert light energy into chemical energy.

Stroma

The dense fluid within the chloroplast surrounding the thylakoid membrane & containing ribosomes & DNA I involved in the synthesis of organic molecules from carbon dioxide & water

Grana

A stack of membrane - bounded thykaloïds in the chloroplast. Grana function in the light reactions of photosynthesis.

Chlorophyll

Agreen pigment located in membranes within the chloroplasts of plants & algae & in the membranes of certain prokaryotes. Alpha chlorophyll participates directly in the light reactions, which convert solar energy to chemical energy.

Photosystems

A light capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light- harvesting complexes. There ave two types of photosystems, 1& 2, they absorb light best at different wavelengths

Light dependent reactions

Carbon fixation ( Calvin cycle )

The second of two major stages in photosynthesis ( following the light reactions )involving the fixation of atmospheric carbon dioxide & reduction of the fixed carbon into carbohydrate

Krebs cycle ( citric acid cycle )

A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing acetyl CoA ( derived from pyruvate )to carbon dioxide this occurs within the mitochondrion in eukaryotic cells & in the cy to sol of prokaryotes; together with pyruvate oxidation, the second majorstage in cellular respiration.

Election transport chain

A sequence of electron carrier molecules ( membrane proteins) that shuttle electrons down a series of redox reactions that release energy used to make ATP.

ATP synths is

Osmosis

The diffusion of free water across a selectively permeable membrane

Homeostasis

The steady-state physiological condition of the body .

Osmoregularity