Transcript Chapter 3- Part 1 Cells PPT

Levels of Structural Organization
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Cytoplasmic Organelles
Figure 3.4
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I. Anatomy of the Generalized Cell
 Cells are the building blocks of
all living things
 Carry out all chemical activities
needed to sustain life
 The activity of a cell depends on
its shape and the number and
types of cellular organelles.
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 The trillions of cells in the human body
have about 200 different varieties.
 All cells have three main regions:
1. Nucleus
2. Cytoplasm
3. Plasma membrane
Figure 3.1a
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1. Nucleus
 Control center
of the cell
 Contains
genetic
material (DNA)
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2. Cytoplasm
Cytoplasm is the material outside the nucleus and
inside the plasma membrane.
Contains three major elements:
1. Cytosol- fluid that suspends other elements
2. Organelles- “little organs” that perform
functions for the cell
3. Inclusions- chemical substances such as
stored nutrients or cell products
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3. Plasma Membrane
 Semi-permeable barrier for cell contents
 Structure: Double phospholipid layer that also
contains proteins, cholesterol, and glycoproteins
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Cytoplasmic Organelles
Figure 3.4
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1. The Nucleus
 Chromatin
 Composed of DNA and protein and is scattered
throughout the nucleus
 Only present when the cell is not dividing
 It condenses to form chromosomes when the cell
divides
 Nuclear envelope (membrane)
 Barrier of the nucleus
 Contains nuclear pores- that allow for exchange of
material with the rest of the cell
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2. Plasma Membrane
 Outer barrier of the
cell
 Controls what
goes in and out of
the cell (selectively
permeable)
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Membrane Anatomy
 Structure of plasma membrane consists of 2 layers
of phospholipids with proteins and other molecules
floating in the layers
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Phospholipids
Forms the majority of
the double layer
Hydrophilic (water
loving) “heads” arrange
themselves together
and form the inner and
outer surfaces of the
membrane
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 Hydrophobic (water
hating) “tails” arrange
themselves together
and form the interior
of the membrane
 Many molecules are
not able to pass
through the
membrane and need
other specialized
molecules to help
them move in and out.
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Proteins
 can form channels and carriers to allow substances
to move in and out
Glycoproteins
 Membrane proteins that have carbohydrates
attached
 Determine blood type; involved in cell to cell
interactions; site where toxins, bacteria, and
viruses can bind to
Cholesterol
 Found throughout the membrane to keep it more
fluid
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Plasma Membrane Specializations
 Microvilli
 Finger-like projections that
increase surface area for
absorption
 Found in cells that line certain
organs, such as the small intestine
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Cytoplasmic Organelles
Mitochondria
 “Powerhouses” of the cell
 Carry out reactions where oxygen
is used to break down food
 Provides ATP for cellular energy
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Cytoplasmic Organelles
Ribosomes
 Sites of protein synthesis
 Found at two locations
 Free in the cytoplasm
 As part of the rough ER
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Cytoplasmic Organelles
Endoplasmic reticulum (ER)
 Fluid-filled tubules for carrying
substances
 Two types of ER
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Cytoplasmic Organelles
Rough endoplasmic reticulum
 Studded with ribosomes
 Synthesizes proteins
Smooth endoplasmic reticulum
 Functions in lipid metabolism and
detoxification of drugs and
pesticides
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Rough Endoplasmic Reticulum
Ribosome
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).
Protein
The protein is packaged in a
tiny membranous sac called a
transport vesicle.
Transport
vesicle buds off
Protein inside
transport vesicle
The transport vesicle buds from
the rough ER and travels to the
Golgi apparatus for further
processing or goes directly to
the plasma membrane where its
contents are secreted.
Figure 3.5
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Golgi apparatus
 Modifies and packages proteins that are sent to it by
the rough ER
Proteins in cisterna
Rough ER
Cisterna
Lysosome fuses with
ingested substances
Membrane
Transport
vesicle
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Pathway 3
Golgi
apparatus
Pathway 1
Pathway 2
Secretory vesicles
Proteins
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Secretion by
exocytosis
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Golgi vesicle containing
membrane components
fuses with the plasma
membrane
Plasma membrane
Figure 3.6
Extracellular fluid
Cytoplasmic Organelles
Lysosomes
 Contain enzymes that digest worn-out or
non-usable materials within the cell
Peroxisomes
 Membranous sacs of oxidase enzymes
 Detoxify harmful substances such as
alcohol and formaldehyde
 Break down free radicals (highly reactive
chemicals)
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Cytoplasmic Organelles
Centrioles
Builds the structures
necessary for cell
division
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Cytoplasmic Organelles
Figure 3.4
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Cell Diversity
Cells that connect body parts
Fibroblast-elongated cell in connective tissue; has large
rough ER and golgi; important in building collagen
(important protein in the skin)
Erythrocyte- Red Blood Cell- concave shape provides
extra surface area to carry oxygen; contains so much
pigment that it has no other organelles.
Figure 3.8a
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Cell Diversity
Epithelial cell-hexagon shape, usually found in the lining
of organs and other body surfaces; packs together in sheets
and resists tearing when pulled
Figure 3.8b
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Cell Diversity
Skeletal muscle and smooth muscle cells- elongated and
can shorten and extend to move bones or change size of
organs
Figure 3.8c
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Cell Diversity
Fat cell- huge circular shape; has a large lipid droplet in
the cytoplasm; used to store lipids for energy
Figure 3.8d
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Cell Diversity
Macrophage- has many lysosomes that help digest
bacteria and viruses; important cell in the immune system
Figure 3.8e
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Cell Diversity
Nerve cell- extensive plasma membrane and has a large
rough ER; helps send signals throughout the body and
allows the brain to communicate with the body
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Cell Diversity
Oocyte- largest cell in the body; has many copies of the
organelles; female reproductive cell
Sperm- elongated shape; only cell that has a flagella; large
amounts of mitochondria; male reproductive cell
Figure 3.8g
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