Cells Flashcards
cell wall
protects cell from outside environment and maintains shape. Also prevents cell from bursting if internal pressure rises
Plasma membrane
semi-permeable membrane that controls the substances moving into and out of cell. Contains integral and peripheral proteins. Substances pass through by active or passive transport
Cytoplasm
contains enzymes used to catalyze chem reactions of metabolism and contains DNA in region called nucleoid. Ribosomes found in cytoplasm
Pili
help bacteria adhere to each other for exchange of genetic material. Helps attach to diff substances
Flagella
propells bacteria to move around by the use of the motor protein
ribosomes
site of protein synthesis. contributes to protein synthesis by translating messenger RNA
nucleoid
region containing naked DNA — stores hereditary material (genetic info) — controls cell and will be passed on to daughter cells
plasmid DNA
additional DNA mole that can exist and replicated independently of the genophore — it can be transmitted between bactorial species
Capsule
thick polysaccharide layer — protection against dessication (drying out) and phagocytosis
mesosome
sight of respiration
cytosol
refers to semifluid portion of cytoplasm. includes cytosol and organelles (except nucleus). Contains proteins, lipids, carbs, salts and other solutes. Chem reactions take place
Cytoskeleten
small tubules and filaments — suspended in cytosol and provides support and shape
nuclues
control center. contains DNA
Rough EDR
ribosom embedded on surface. pack proteins — secreted into sacs
smooth EDR
involved production of lipids (cholesteral) and (sex) hormones. Also in detoxifaction of substances
Golgi apparatus
processing proteins
lysosomes
holds digestive enzymes capable of digesting substances inside cell. engulf old, worn out organelles
mitochondrian
‘powerhouse’ of cell — produce ATP, responsible for aerobic respiration
plastids
occur in plants and photosynthetic eukaryotes. incl chloroplasts (site of photosynthesis), lecicoplasts (stores starch, proteins and oils) and chromoplasts
vacuoles
storage. salts, ions and water
centrioles
animal cells only. composed of set of microtubules and form spindles during cell division
basic 3 components of cell theory
- all orgs composed of 1+ cells
- Cell is basic unit of life in all living
- All cells produced by division of pre-existing cells
7 functions of life
- Nutrition
- Metabolism
- Growth
- Response
- Excretion
- Homeostasis
- Reproduction
two key properties of stem cells
- stem cells can divide again and again to produce new cells —– useful for growth of tissues or replacement of cells lost or damaged
- not fully differentiated — can differentiate to produce differet cell type
Sources of stem cells
embryonic, cord blood, adult,
Eukaryotics
have compartment in cells that contain chromosoms
nucleus bounded by nuclear envelope consisting of double layer of membrane
Prokaryotics
do not have nucleus
were 1st org to evolve on earth and still have simplest cell structure
mostly small
found almost everywhere; soil, water, skin etc
endocrine gland cells
secrete hormones into blood stream
exocrine gland cells
secrete digestive enzymes into duct — carries them to small intestine where they digest food
hydrophilic
attracted to water
hydrophobic
not attracted to water
Common features of cells
Every cell surrounded by membrane
Cells contain genetic material – stores all instructions needed for cell’s activities
Many these activities chem reactions — catalysed by enzymes
Cells have own energy release system powers all of cells activities
How does striated muscle conform to and question cell theory
Conform: surrounded by membrane have own genetic material and energy release system Deviates: much larger ave 30mm length many nuclei
How does giant algae conform to and question cell theory
Conforms:
store genes inside nuclei
Deviates:
large — 100mm
SA: V ratio – if too small?
in absorbing and excreting substances
substances not enter cell as quickly as required, and waste products accumulate — produced more rapidly than excreted
SA:V ratio — if too small?
in heat production and loss
cells may overheat
because metabolism produces heat faster than is lost over surface
What is tissue?
when a group of cells specialize in the same way to perform the same function
by becoming specialized carry out role more efficiently
develop ideal structure
Gene being expressed
when gene is being used in the cell
How does cell differentiation happen?
a diff sequence of genes is expressed in diff cell types
control of gene expression therefore key to development
two properties of stem cells
can divide again and again — to produce quantities of new cells, for growth of tissues or replacement
not full differentiated — can differentiate
difference betw Eukaryotes and Prokaryotes
E — have nucleus, – compartmentalised
P — dont
Advantages of being compartmentalised
- more concentrated enzymes and substrates
- substances that could cause damage can be kept inside membrane of an organelle
- conditions maintained at ideal level for particular process
- organelles can be moved around
Function of Palisade mesophyll
cell type carries out most photosynthesis in leaf
Amphipathic
substances part hydrophilic and part hydrophobic e.g phospholipid
Functions of membrane proteins
- hormone binding sites
- immobilized enzymes with active site on outside
- cell adhesion
- cell to cell communication
- channels for passive transport
- pumps for active transport
Role of cholesterol
- disrupts regular packing of tails so prevents them from crystallizing and behaving as a solid
- restricts molecular motion
- reduces permeability to hydrophilic particles
What are vesicles
small sacs of membrane with droplet of fluid inside
What can vesicles be used for?
movement of materials around inside cells or to release materials from cells
what are the four methods of moving particles across membranes?
simple diffusion
osmosis
active transport
facilitated diffusion
define simple diffusion
spreading out of particles in liquids and gases
move particles from area of lower concentration — down concentration gradient
involves particles passing through phospholipids in membrane
define facilitated diffusion
helps particles pass through from higher to lower concentration
-channels in p memb allow ions and particles that cannot diffuse to pass through
osmosis
passive movement of water moles through partially permeable membrane from an area of higher solute concentration to an area of lower solute concentration
active transport
cells taking in substances against concentration gradient
ATP
pump proteins
Hypertonic solution
solution with higher osmolarity
water leaves cells by osmosis —- cytoplasm shrinks in volume
hypotonic solution
lower osmolarity
cells take in water and swell up
isotonic solution
solution with same osmolarity as cells
water moles enter and leave at same rate — healthy
