Transcript Organelles - kambryabiology

Organelles
Types of Organelles
• Nonmembranous organelles:
– no membrane
– direct contact with cytosol (cytoplasm)
• Membranous organelles:
– covered with plasma membrane
• 6–types
offrom
nonmembranous
organelles:
isolated
cytosol (cytoplasm)
– cytoskeleton
– microvilli
-cilia
– centrioles
– ribosomes
– proteasomes
How does the nucleus control the cell?
• Is the cell’s control center
• Nucleus:
– largest organelle
• Nuclear envelope:
– double membrane
around the nucleus
• Perinuclear space:
– between 2 layers of
nuclear envelope
• Nuclear pores:
– communication
passages
Within the Nucleus
• DNA:
– all information to build and run organisms
• Nucleoplasm:
– fluid containing ions, enzymes, nucleotides, and
some RNA
• Nuclear matrix:
Nucleoli
in
Nucleus
– support filaments
• Are related to protein production
• Are made of RNA, enzymes, and histones
• Synthesize rRNA and ribosomal subunits
Ribosomes
SEM of rough ER (ribosomes
attached to membranes)
Ribosomes
• Two types:
– free ribosomes in cytoplasm:
• proteins for cell
– fixed ribosomes attached to ER:
• proteins for secretion
• Translate the genetic code into proteins.
• Build polypeptides in protein synthesis
• 60% RNA and 40% protein.
Proteasomes
(found in the nucleus and the cytoplasm)
• Contain enzymes (proteases)
• Disassemble damaged proteins for recycling
Endoplasmic reticulum
TEM of rough ER (ribosomes
attached to membranes)
Endoplasmic Reticulum (ER)
• endo = within, plasm = cytoplasm, reticulum = network
•
•
•
•
•
•
•
Little net
Network of interconnected closed membrane vesicles
Single membrane
Divides cell into compartments
Place of protein and phospholipids synthesis
Connected with the nuclear envelope
Cisternae are storage chambers within membranes
Functions of ER
•
•
•
•
Synthesis of proteins, carbohydrates, and lipids
Storage of synthesized molecules and materials
Transport of materials within the ER
Detoxification of drugs or toxins
• It is of 2 types:
1. Rough ER
2. Smooth ER
Rough Endoplasmic Reticulum
• Network of continuous sacs,
studded with ribosomes.
• Manufactures, pro-cesses, and
transports proteins for export
from cell.
• Continuous with nuclear
envelope.
• Surface covered with ribosomes:
– active in protein and
glycoprotein synthesis (late r
inserted in the cell membrane
and secreted from the cell)
– folds polypeptides protein
structures
– encloses products in
transport vesicles
Smooth Endoplasmic
Reticulum
• Similar in appearance to rough ER, but
without the ribosomes.
• Involved in the production of lipids,
carbohydrate metabolism, and
detoxification of drugs and poisons.
• Ca (2+) storage
• Synthesizes lipids and carbohydrates:
–
–
–
–
phospholipids and cholesterol (membranes)
steroid hormones (reproductive system)
glycerides (storage in liver and fat cells)
glycogen (storage in muscles)
Golgi complex
TEM of Golgi complex
ER and Golgi complex
The ER and Golgi
complex work
together to secrete
substances from
the cell (via
exocytosis)
Golgi Bodies
– Contains several hundred flattened
compartments and vesicles
– Secretory vesicles:
• modify and package products for exocytosis
– Membrane renewal vesicles:
• add or remove membrane components
– Transport vesicles:
• Carry materials to and from Golgi apparatus
Golgi Bodies
Lysosomes
SEM of two lysosomes
containing undigested
material
Cell death caused by
lysosomes removes
webbing
Lysosome Functions
• Powerful enzyme-containing vesicles:
– lyso = dissolve, soma = body
• Clean up inside cells:
– break down large molecules
– attack bacteria
– recycle damaged organelles
– ejects wastes by exocytosis
• Primary lysosome:
– formed by Golgi and inactive enzymes
• Secondary lysosome:
– lysosome fused with damaged organelle
– digestive enzymes activated
– toxic chemicals isolated
Chloroplasts
TEM of
chloroplasts
Chloroplasts
•
Photosynthetic plant cells also contain chloroplasts (a plastid) that capture
energy from sunlight.
•
They produce and store carbohydrates like miniature gardens and warehouses.
•
LOCATION
inside photosynthetic cells only, suspended in the cytosol
•
DESCRIPTION
 green, disk shaped
 contains chlorophyll and the enzymes required for photosynthesis
FUNCTION
• absorb sunlight energy
• photosynthesis occurs here: glucose is synthesized from Carbon Dioxide and
water
Chloroplast
PRESENT IN:
• PROKARYOTIC CELLS?
NO
• PLANT CELLS?
YES
• ANIMAL CELLS?
NO
VISIBLE WITH:
• LIGHT MICROCOPE?
YES
• ELECTRON
MICROSCOPE?
YES
Mitochondria
TEM
SEM
Notice the many folds
Mitochondria
Tubular susage shaped
Double membrane
Own DNA and ribosomes
Have smooth outer membrane and folded inner membrane
(cristae)
Matrix:
– fluid around cristae
Mitochondrial Function
• Mitochondrion takes chemical energy from food
(glucose):
– produces energy molecule ATP
Figure 3–9b
Animal and plant
cells
Animal cell
Plant cell
Cell skeleton
Three structures that make up the cytoskeleton of a cell
The Cytoskeleton
(Structural proteins for shape and strength)
• Microfilaments
• Solid rods of globular proteins.
• Important component of cytoskeleton which
offers support to cell structure.
Thin filaments composed of the protein actin:
•
•
•
•
•
provide additional mechanical strength
durable (collagen)
strengthen cell and maintain shape
stabilize organelles
stabilize cell position
• Microtubules
– Large, hollow tubes of
tubulin protein:
• attach to centrosome
• strengthen cell and
anchor organelles
• change cell shape
• form spindle
apparatus
• Microvilli
• Increase surface area for
absorption
• Attach to cytoskeleton