Cell Structure and Function Flashcards
Surface Area / Volume Ratio
- a cell increases in volume, the proportionate amount of SA decreases
- ^ V > v SA ; v V > ^ SA
- amount of SA affects ability of cell walls to exchange materials into and out of the cell
The Cell Theory
1- all organisms are composed of 1+ cells
2- are the basic living unit of structure and function in organisms
3- all cells come from preexisting cells (by self-reproduction)
Cell
- The structural & functional unit of an organism
- the smallest structure capable of performing all the functions necessary for life.
- the molecules that serve as food or composition of a cell are NOT alive
- smallest organism: unicellular
- largest: multicellular
Unicellular
Made of 1 cell
Multicellular
Made up of more than 1 cell
Prokaryotic Cells
- lack membrane-enclosed structures within them (eg. nucleus); structurally simple
- metabolically diverse (more than eukaryotes)
- can synthesize all their structural components from very simple, even inorganic molecules
- adapted to most types of environments
- generally exist as unicellular organisms
Plasma Membrane
- all cells surrounded by plasma membrane made up of a phospholipid bilayer.
- regulates what enters or exits a cell
Cytoplasm
- contents of a cell btwn nucleus & plasma membrane
- contains organelles
- composed mostly of water, salts, & dissolved organic molecules
Prokaryotic Cell Wall
-located outside of the plasma membrane
Capsule
Gelatinous layer surrounding the cell of algae and certain bacteria that provides further protection for prokaryotes
Slime Layer
Gelatinous sheath surrounding certain prokaryotes, sometimes even added on to the capsule
Flagellum
pl. Flagella
Long, slender “tail” used for locomotion by using it like a propeller to move rapidly in fluid mediums
- enclosing matrix area in 9+2 pattern of microtubule triplets
- triplets x 3 connected to central OO
Fimbria
pl. Fimbriae
Short hairlike bristles that help prokaryotes to adhere/attach to surfaces
Nucleoid
Region of a prokaryotic cell where the free-floating DNA is located; not bound by a nuclear envelope
Prokaryotic Ribosome
RNA & proteins in 2 subunits; site of protein synthesis in the cytoplasm
-ribosomes of prokaryotes are smaller & structurally different than those in eukaryotic cells
Eukaryotic Cells
- structurally complex
- have a nucleus
- possesses membrane-bound organelles
eg. animal, plant, fungi, & protists
Plant Cell Wall(s)
- cells have a permeable but protective cell wall + plasma membrane
- composition: cellulose fibrils
- can have 2 cell walls
- function: support and protect
Organelles
- found in eukaryotic cells
- tiny specialized structures that perform specific cellular functions
- often membranous
- found in the cytoplasm
Nucleus
- stores genetic material (DNA)
- composed of: nuclear envelope, nucleolus, nuclear pores, nucleoplasm
Nuclear Envelope
- continuous double membrane of phospholipids w/polar liquid btwn the layers in order to thicken the envelope btwn polar heads
- connected to RER
Nuclear Pores
Pores in the nuclear envelope that allows bidirectional transport of proteins & ribosomal subunits (eg. mRNA)
Nucleoplasm
Semifluid medium of the nucleus containing chromatin.
Nucleolus
pl. Nucleoli
- dark-staining spherical body in the nucleus that produces ribosomal subunits
- where rRNA is produced
DNA
- every cell contains identical sets of DNA
- but in each cell type, certain genes are turned off/on
Chromatin
- DNA @ rest
- DNA lightly wrapped around histones (proteins)
- G1
Chromosomes
- location: nucleoplasm
- human cells: 46 chromosomes
- chromatin that is coiled, looped & condensed
- G2, P, M
Ribosomes
- location: individually in cytoplasm (or in groups called polyribosomes) or attached to RER
- 2 subunits: ‘large’ & ‘small’ (hamburger) complexes of rRNA + protein molecules
- function: synthesis of proteins using mRNA as a template
Vesicles
- small, membrane-bounded sac (phospholipid bilayer) that stores substances within a cell
- incoming (pinched from plasma membrane + macromolecule)
- transport (from GA or ER)
- secretory (from GA)
Endoplasmic Reticulum
A complicated system of membranous channels + sacs which is the site of protein and lipid production within the cell
-rough ER & smooth ER
Rough Endoplasmic Reticulum (RER)
- directly connected to nuclear envelope
- studded w/ribosomes on outward face
- proteins synthesized from ribosomes & pass into interior of RER to be processed/modified
- proteins destined for cell membrane/secretion
Smooth Endoplasmic Reticulum (SER)
- continuous w/RER; lacks ribosomes
- synthesizes phospholipids
- performs variety of other functions depending on the kind of cell it is in
Golgi Apparatus
- location: cytoplasm
- composed: inner half/face toward ER & outer half/face to cell wall
- collects, sorts, packages/modifies, distribute, makes lysosomes
- receives proteins from RER w/’zip codes’ to indicate where they should be sent (or if they should be modified)
Secretion
Release of a substance by exocytosis or ‘steps to secretion’
Lysosomes
- membrane-bound vesicles produced by GA w/hydrolytic digestive enzymes already inside
- hydrolyze incoming/foreign substances
- autodigestion: when lysosomes digest parts of the cell that are no longer useful
Vacuole
-membranous sacs that store substances
AC- tiny and filled w/water-based solutions
PC- large central vacuole that lends support to cell wall using turgor pressure
-also contains sugars, salts, pigments, and toxins
Peroxisomes
- initially empty membranous sac
- filled w/enzymes from cytoplasmic ribosomes (transported by carrier proteins) that typically hydrolyze molecules into H2O2 (hydrogen peroxide)
- catalase (another peroxisomal enzyme) immediately hydrolyzes H2O2 into H2O + O to hydrate body
- enzyme type + function depends on its location
Chloroplast
- site of photosynthesis
- components: 2 separate bilayers (not touching; phospholipids), stroma, grana, thylakoids
- contains: own DNA, ribosomes, enzymes
- can survive on its own as a prokaryote
Stroma
- located: inside double membrane of chloroplast
- fluid-filled space that contains single circular DNA + ribosomes
Photosynthesis
-how plants make their own food using the energy of the sun
-solar energy + H2O + CO2 = carbohydrates + O
PC-can cycle btwn photosynthesis & cellular respiration
Intermediate Filaments
- located: inside cytoplasm attached to nucleus
- support 1) nuclear envelope + 2) plasma membrane
- cell-cell junctions, such as holding skin cells tightly together
- “yarn”
Cellular Respiration
- metabolic reaction that break down carbohydrates to produce ATP molecules (/fatty acids/amino acid)
- location: mitochondria
- carbohydrate + O = CO2 + H2O + store energy (in ATP)
Mitochondria
- all eukaryotic cells
- site of cellular respiration
- structure: no-contact double membrane, matrix (own DNA, ribosomes, enzymes), crista (inner membrane)
- can exist independently as a prokaryote
Centrosome
-Central MTOC of cells
Centrioles
- located: in centrosome @ right angles to each other (pair)
- function: involved in cell division providing tracks for organelles
- 9+0 pattern of microtubule triplets
- triplets x 9 connected to central O
Cilia
-hair-like projections that aid cell movement
EuC-much shorter than flagella
-9+2 pattern of microtubule triplets
-triplets x 9 connected to central OO
Crista
pl. Cristae
Inner membrane of mitochondria that ‘invaginates’/folds to form finger-like projections to increase SA to accommodate protein complexes & other participants in ATP production
Cytoskeleton
- internal framework of a cell, from nucleus to plasma membrane
- assists in movement of cell & organelles
- assemble/disassemble as needed
- types: actin filaments, intermediate filaments, microtubules
Actin Filaments
- location: anchored to plasma membrane
- function: supports the membrane by weaving into a mesh-like structure + movement of cells/organelles
- “rope”
Microtubules
- assembly: under control of Microtubule Organizing Center (MTOC)
- imp. MTOC: centrosome (center)
- sends vesicles/organelles on ‘tracks’ to anywhere
- “thread”
