Download cell structure and function

CELL STRUCTURE AND FUNCTION
All living things share common compounds:
water: universal solvent – smaller is better
transport
hydrolysis
carbohydrates: source of energy
cell recognition
(monosaccharides, disaccharides, polysaccharides)
lipids: source of energy
does not dissolve in water
(saturated, unsaturated, polyunsaturated)
proteins: cellular growth and repair
enzymes
aid in diffusion and transport
(amino acids)
nucleic acids: genetic codes and transmission
DNA: reproduction and function
double strand
RNA: protein synthesis
All livings need:
water
shelter
energy- life processes
Photosynthesis: energy from sun stored in chemical bonds of
sugars
Respiration: chemical reaction aided by enzymes to break
bonds to release energy.
aerobic-oxygen=a lot of energy released
anaerobic-lack of oxygen=not so much energy
released
Chemosynthesis: unicellular organisms obtain energy from
inorganic compounds=minerals=little energy obtained
autotrophs
heterotrophs
All living things will:
grow(increase in the number of cells) and develop
(organs become more complex, mature)
respond to environment: stimulus and appropriate
response
reproduce: to continue the species
sexual: 2 cells-2 sets of DNA-similar offspring
asexual: 1 cell-1 set of DNA-identical offspring
stable internal environment: homeostasis
temperature (rise in could denature enzymes)
blood pressure
respiration rate
metabolism rate
heart rate
THE CELL THEORY
1. ALL LIVING THINGS ARE
COMPOSED OF CELLS.
2. BASIC UNIT OF STRUCTURE
AND FUNCTION
3. PRODUCED FROM OTHER
CELLS.
CELL MEMBRANE
thin, flexible barrier
cholesterol-lipid
selectively permeable
CELL WALL
rigid, protective barrier
cellulose –carbohydrate
polysaccharide
Nucleus: brain of the cell
contains genetic material – codes for function
controls cell’s activities
prokaryotes: cell membrane and cytoplasm
NO NUCLEUS
bacteria, staph, ecoli
Eukaryotes: cell membrane, cytoplasm, and nucleus
NUCLEAR ENVELOPE
Double membrane
*pores
CHROMATIN
DNA+protein
NUCLEOLUS
Production of
proteins
Cytoplasm: jelly like substance that fills the cell
70% water
Cytoskeleton: network of protein filaments
maintains shape
Microtubules: cell movement = cilia, flagella
cell division=centrioles
Microfilaments: structure
Ribosomes: synthesis of proteins using codes from
RNA
Endoplasmic Reticulum: movement of materials
rough: synthesis of proteins contain ribosomes
smooth: contain enzymes-specialized tasks=
synthesis of lipids
Golgi bodies: package and transport materials
in the cell, especially proteins:
produced in RER
Lysosomes: cell’s waste disposal system
enzymes break down lipids, carbs and proteins
digest old organelles
Vacuoles: storage for water, salts, proteins, carbs
plants – one large =storage and support
**vesicles: small vacuoles used to transport
Chloroplasts: chlorophyll (Plastids: leukoplasts/chromoplasts)
trap sunlight for photosynthesis
contain nucleus=reproduction
Mitochondria: powerhouse of the cell
convert energy from food into ATP
involved in cell death, cell division
cellular respiration.
contain nucleus=reproduction
inherited from mother
two membranes
Cell membrane – selectively permeable
protects, supports
takes in food and water
eliminates wastes
structure of membrane: double layer made up
of lipids called lipid bilayer=tough, flexible
Diffusion: movement of materials through the
membrane based on concentration:
high concentration to low concentration
**when concentration inside is equal to concentration
outside the system has reached equilibrium
Molecules will continue to move into and out of
the cell to maintain equilibrium.
Osmosis: diffusion of water across a selectively
permeable membrane.
Isotonic: equal in out
Hypotonic: more in than out swollen cell
Hypertonic: more out than in shrunken cell
Osmotic pressure: force exerted by too much
fluid inside a cell-a result of movement of
fluid from high concentration to low concentration.
This pressure could cause cells to burst.
Freshwater would be a problem for most cells in a
living organism because of the salt content in the
fluids that surround cells.
In large living organisms, cells do not come in contact
with fresh water because these cells are surrounded
by fluids such as blood which is isotonic.
Cells that would come in contact with fresh water
such as plants and bacteria correct this osmotic
pressure in two ways:
1. cell wall prevents cells from expanding
2. contractile vacuoles-vacuoles that have the
ability to contract or pump rhythmically
to push water out of the cell.
Some molecules such as water, alcohol, and small
lipids can diffuse or move through the lipid
bilayer into the cell. Others cannot-size, polarity.
Facilitated diffusion is a process that uses special
proteins to allow these molecules to pass into
the cell
http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter38/how_facilitated_diffusion_works.
html
Summary of diffusion
SODIUM
CALCIUM
POTASSIUM
Transport
protein
Na
These elements are important for muscle
contraction such as the …….
Active transport-diffusion that requires energy
low concentration to high concentration
Seen mostly with ions such as potassium and
sodium. Concentrations of these ions are lower
outside the cell than inside the cell.
Special proteins imbedded in the cell membrane
act like pumps to pump these ions into the cell.
If a molecule is to be transported from an area of low
concentration to an area of high concentration, work
must be done to overcome the influences of diffusion and
osmosis. Since in the normal state of a cell, large
concentration differences in K+, Na+ and Ca2+ are
maintained, it is evident that active transport
mechanisms are at work.
Two other ways cells bring materials in are:
endocytosis: cell membrane engulfs material,
forming a vacuole within in the cytoplasm.
Size is not a factor and material can be a liquid
or a solid
Phagocytosis: engulfs molecules larger than
endocytosis
materials are solids only
Removal of large amount of material are known
as exocytosis- membrane of vacuole fuses
with cell membrane and contents are released
Unicellular: prokaryotes and eukaryotes
may contain chloroplasts
very adaptable
reproduce easily and quickly
offspring are identical
live independently
Multicellular: eukaryotes
interdependent
specialized cells
Levels of organization:
cell
tissue
organ
organ system