cytology powerpoint notes - weebly
TRANSCRIPT
Cytology
Cell Structure and Function
Overview of Animal Cell
Structure
A. Plasma Membrane
B. Cytoplasm
C. Major Organelles
1. nucleus
2. ribosomes
3. endoplasmic reticulum (ER)
4. Golgi complex (apparatus)
5. mitochondria
6. lysosomes
7. peroxisomes
D. Cytoskeleton, Cilia, Flagella
E. Inclusions
F. Extracellular Matrix
The Plasma Membrane
A. Chemical Composition
1. 80% phospholipids
a. "head" region of
molecule is hydrophilic
b. "tail" region of
molecule is hydrophobic
2. 10% proteins - peripheral
and integral
3. 10% cholesterol, glycolipids,
carbohydrates
B. Structure
1. phospholipid bilayer - two layers
of phospholipids with "head"
regions pointing inward and
outward while "tail" regions
intermingle in the middle of the
sandwich.
• Fluid motion of these molecules
is described as a “fluid mosaic”.
Here you can see the lipid bilayer with both integral
and peripheral proteins embedded in the
membrane.
2. integral membrane proteins
a. float in or completely across
lipid bilayer
b. act as selective channels for
transport
c. act as receptor sites for
messengers(hormones)
3. peripheral membrane proteins
a. lie on inner/outer surface of
lipid bilayer
b. many have enzymatic role
c. structural function in tissue
organization
C. Primary Functions
1. selective transport of materials
in and out of cell.
2. maintain cell structure and
intracellular climate.
Cytoplasm
A. Composition and Structure
1. 90% water, 10% protein,
carbohydrate, lipid, salts
2. colloids - collections of
organic molecules
3. jelly-like fluid surrounding
the nucleus
4. criss-crossed by
cytoskeleton that holds
cell shape
B. Function
1. site of many enzyme
controlled reactions
2. site of both synthesis and
degradation reactions
3. intermediate area for storage
and cell transport
Nucleus
A. Structure and Composition
1. nuclear membrane - double
lipid bilayer
2. perinuclear cisterna
3. nuclear pores
4. nucleoplasm (karyolymph)
5. Deoxyribose Nucleic Acids(DNA)
a. chromatin - dispersed
DNA, invisible
b. chromosomes - condensed
DNA, only when dividing
6. nucleolus - site of ribosome
synthesis
B. Primary Functions
1. house and protect hereditary
material (DNA)
2. copy DNA to RNA so proteins can
be manufactured
3. produce ribosomal RNA (rRNA) to
make ribosomes
Ribosomes
A. Composition and Structure
1. rRNA (made in nucleus) and
associated proteins
2. two subunits forming a 3-D
granule
B. Primary Functions
1. only site of protein synthesis
2. "read" the messenger RNA sent
out from nucleus
3. free ribosomes - scattered
throughout cytoplasm
4. attached ribosomes - found on
endoplasmic reticulum
Endoplasmic Reticulum (ER)
A. Structure
1. cisternae - double membranous sacs
2. extend directly from the nuclear
membrane
3. granular (rough) ER - have ribosomes
attached
4. agranular (smooth) ER - no ribosomes
B. Primary Functions
1. transport, storage, packaging of materials
2. surface area for cellular reactions
3. granular ER
a. synthesis of proteins bound for
secretion
b. passes proteins to Golgi for processing
4. agranular ER
a. storage area for Ca++ (muscle cells)
b. lipid synthesis inactivation
c. detoxification of harmful
compounds(liver)
Golgi Complex (Apparatus)
A. Structure
1. cisternae - lined up in
stacks next to nucleus
2. cis, medial, and trans parts
(Cis face receives material from the ER.
The trans face forms transport vesicles
that send material to the cell membrane
for secretion)
B. Primary Function
1. process, sort, package, deliver
proteins (UPS)
2. cis - closest to ER, receives new
proteins
3. medial - alters protein to functional
form
4. trans - forms secretory granules for
protein release:
a. digestive enzymes
b. antibodies
c. secretory glands
d. extracellular matrix material
Mitochondria
A. Structure
1. two-membrane structure
a. outer mitochondrial
membrane
b. inner mitochondrial membrane
(cristae)
2. matrix - within the inner
membrane
B. Primary Functions
1. powerhouse of the cell
2. foodstuffs (glucose) broken down in
cytoplasm converted to useable energy
"currency" called ATP
3. inner membrane contains
"respiratory" enzymes
C. Varied Distribution
1. low energy required - fewer
mitochondria
2. high energy required - more
mitochondria
a. muscle cells
b. liver cells
c. kidney tubule cells
Lysosomes
A. Structure
1. single membrane enclosed
spheres
2. primary lysosome - bud-off from
Golgi complex
3. secondary lysosome - when
fused with a vacuole
B. Primary Functions
1. breakdown (digestion) of compounds and
old parts
2. autophagy - "self eating" reuse old
organelles
3. autolysis - "self destruction" of entire cell
4. release digestive enzymes to outside
a. sperm entering egg during
fertilization
b. during repair of bodily injury
c. osteoclasts - during bone growth
Peroxisomes
A. Structure
1. small, single membrane enclosed
spheres
B. Primary Function
1. breakdown hydrogen peroxide (toxic
to cells)
2. catalase - enzyme that catalyzes
breakdown
Cytoskeleton
A. Microfilaments
1. 6 nanometers in diameter
2. made up of subunits called actin
3. support and cell shape
4. movement
a. muscle contraction
b. white blood cells (phagocytes)
B. Microtubules
1. ~24 nanometers in diameter
2. made up of subunits called tubulin
3. involved in intracellular transport
a. move organelles around like a
highway
4. involved in amoeboid motion of cells
(phagocytes)
5. chief components of cilia and flagella
C. Cilia and Flagella
1. both consist of microtubules (9+2
arrangement)
2. flagella very large for cell locomotion
(sperm)
3. cilia very small, fingerlike projections
a. epithelium of respiratory tract
b. lining of digestive tract (intestinal villi)
Cell Inclusions
A. Structure
1. conglomeration of molecules of
same type
2. melanin - pigment in skin, hair,
eyes
3. glycogen - glucose storage - liver
and muscles
4. lipids - stored in fat cells
(longterm energy)
Extracellular Materials
A. Different Types
1. interstitial (extracellular) fluid
2. plasma - liquid portion of blood
3. secretory material (mucus, saliva,
sweat)
4. extracellular matrix (binding cells into
tissue)
B. Fibrous Extracellular Components
(thread-like)
1. collagen - primary subunit of fibrous
components
2. collagenous fibers - bone, cartilage,
tendon, ligaments.
3. reticular fibers - fat, muscle, nerve, vessels
4. elastic fibers - (elastin) skin and blood
vessels