Cell Structure Notes

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Transcript Cell Structure Notes

Cellular Structure
SOL BIO 4.a-c
1
Cell Theory

The cell theory is the unifying theme in biology
because it emphasizes the similarity of all living
things.
 All organisms are composed of one or more
cells.
 Cells are the smallest living units of all living
organisms.
 Cells arise only by division of a previously
existing cell.
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Cell Characteristics

Cells contain specialized structures to
perform functions necessary for life.

Cellular activities necessary for life include
chemical reactions that facilitate:
 acquiring energy
 reproduction
 adaptation
 maintaining homeostasis
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Cell Characteristics
The basic processes necessary for living things to
survive are the same for a single cell as they are for
a more complex organism.
 A single-celled organism has to conduct all life
processes by itself.
 A multi-cellular organism has groups of cells that
specialize to perform specific functions.

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Cell Characteristics
All cells contain:
 Genetic material





single circular molecule of DNA in prokaryotes
double helix located in nucleus in eukaryotes
Cytoplasm jelly-like substance that fills the
cells interior
Phospholipids
Plasma membrane encloses the cell
 – phospholipid bilayer
Membrane
proteins
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Cell Types

Cell structure is one of the ways
in which organisms differ from
each other.
 2 Types of Cells
•Prokaryote
•Eukaryote
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Prokaryotic Cells

Earth’s first cells were prokaryotes.

The simplest life forms are the prokaryotes.

Prokaryotic cells exist in two major forms:
eubacteria and archaebacteria.
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Prokaryotic Cells

Prokaryotes are the Earth’s most abundant
inhabitants. They can survive in a wide range of
environments and obtain energy in a variety of
ways.
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Prokaryotic Cells
Prokaryotes are cells that
lack a nucleus and
membrane bound
organelles.

Bacteria and related
microorganisms are
prokaryotes
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Prokaryotic Cells
Some use flagellum for locomotion
 ALL are UNICELLULAR

Bacterial cell wall
Rotary
motor
Flagellum
Sheath
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Generalized Prokaryotic Cell
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Eukaryote
• Eukaryotes arose from
prokaryotes and
developed into larger
more complex organisms.
• Eukaryotes are cells that
contain a nucleus and
organelles surrounded by
a membrane, such as
mitochondria and
chloroplasts.
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Eukaryote
• Can be both
unicellular or
multi-cellular
• Examples of
eukaryotes are:
• All fungus,
plant, and
animal cells
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Generalized Eukaryotic Cell
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Cell Size

Most cells are relatively small because
as size increases, volume increases
much more rapidly.
 longer diffusion time
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Visualizing Cells
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Nucleus
Stores genetic material
 Contains DNA
 site where RNA is made
 Nucleolus: Chromatin and ribosomal subunits


Nuclear envelope:

Double membrane with pores
Largest organelle
 BRAIN of the cell – controls protein synthesis

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Nucleus
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Nucleus
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Nucleus
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Ribosomes

Ribosomes are RNA-protein complexes composed
of two subunits that join and attach to messenger
RNA.
 site of protein synthesis
 assembled in nucleolus
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Ribosomes
They can be found alone in
the cytoplasm or attached
to the endoplasmic
reticulum.
 Alone in cytoplasmmakes proteins for use
within the cell
 Attached to RER- makes
proteins for export out of
the cell
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Endoplasmic reticulum
 transports
materials through the cell
•Rough ER - studded with ribosomes
•Attached to nuclear membrane
•site of protein synthesis and processing
•Smooth ER - lacks ribosomes
•site of synthesis of phospholipids and
the packaging of proteins into vesicles
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Endoplasmic reticulum
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Golgi apparatus
 collection
of Golgi
bodies
•Stacked flattened
sacks
•Site where cell
products are
packaged for export
• Proteins are
modified by being
combined with fats
or carbohydrates
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Golgi apparatus
 Vesicles
then pinch
off from the Golgi
body to be secreted
(outside the cell)
 Involved in the
production of
lysosomes
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Lysosomes

vesicles produced by the
Golgi apparatus.

Lysosomes contain
digestive enzymes and
are involved in
intracellular digestion of
food particles, disease
causing bacteria and
worn out cell parts
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cytoplasm
Endoplasmic
reticulum
Food
vesicle
Golgi
apparatus
Lysosomes
Plasma
membrane
Extracellular
fluid
Digestion of
food particles
or cells
Transport
vesicle
Old or damaged
organelle
Breakdown
of old
organelle
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Vacuoles
Found in PLANT and ANMAL cells
 The vacuole acts a container, storing water and
dissolved particles
 Plants have a large central vacuole for water
storage
 Unicellular animals can use contractile vacuoles
for movement
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Organelles With DNA

Mitochondria


site of cell respiration
Chloroplasts

site of photosynthesis
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Mitochondria
"Powerhouse of the cell" - cellular metabolism
 Structure- outer and inner membranes, cristae
 Found in both plant and animal cells
 Very active cells have more mitochondria

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Chloroplasts
•Chloroplasts are larger and more complex than
mitochondria
•Contain green pigment called chlorophyll that
absorbs sunlight in the first step of photosynthesis
•Found ONLY in PLANTS
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Cell Membrane
•controls what enters
and leaves the cell
•Found in ALL cells
•Phospholipid bilayer
with transport
proteins, and
cholesterol (for
flexibility)
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Cell Wall
•provides support
•Found in PLANT
and BACTERIA cells
•Made from cellulose
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Cytoskeleton

Long slender protein tubes and fibers that extend
from the nucleus to the plasma membrane.

The cytoskeleton contains three types of elements
responsible for cell shape, movement within the
cell, and movement of the cell:
 Actin filaments
 Microtubules
 Intermediate filaments
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Cytoskeleton

The cytoskeleton
contains three types
of elements :
 Actin filaments
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Cytoskeleton
The cytoskeleton
contains three
types of elements:
 Microtubules
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Cytoskeleton
The cytoskeleton
contains three types
of elements:
 Intermediate
filaments
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Cytoskeleton
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Centrioles
•Cylindrical structures found near the nucleus
•Made of hollow, tubular structures arranged in
bundles
•Important in cell division
•Found ONLY in ANIMAL cells
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Plant vs. Animal Cells
PLANT
CELL
HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
DO NOT HAVE:
Centrioles
ANIMAL
CELL
Cell membrane
Mitochondria
HAVE:
Golgi apparatus
Centrioles
Nucleus
Cytoskeleton
DO NOT HAVE:
Ribosomes
Cell Wall
Endoplasmic
LARGE vacuoles
reticulum
Chloroplasts
Lysosomes
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Plant Cell
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Endosymbiosis

Endosymbiosis theory suggests that
eukaryotes arose from a symbiotic relationship
between various prokaryotes.

Heterotrophic bacteria became mitochondria.
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Cyanobacteria became chloroplasts.

Host cell was a large eukaryotic cell.
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Endosymbiosis
Prokaryotic
cell is
engulfed
Eukaryotic cell
Symbiosis
Prokaryotic
cell
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ta_03_14 Evolution of the eukaryotic cell
Slide number: 2
plasma membrane
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ta_03_14 Evolution of the eukaryotic cell
Slide number: 3
plasma membrane
endoplasmic
reticulum
nucleus
nuclear
envelope
Cell has a nucleus
and other organelles.
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ta_03_14 Evolution of the eukaryotic cell
Slide number: 4
aerobic
bacterium
plasma membrane
endoplasmic
reticulum
nucleus
nuclear
envelope
Cell has a nucleus
and other organelles.
Cell has mitochondria.
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ta_03_14 Evolution of the eukaryotic cell
Slide number: 5
aerobic
bacterium
plasma membrane
spirochete
Animal cell has a flagellum.
endoplasmic
reticulum
nucleus
nuclear
envelope
Cell has a nucleus
and other organelles.
Cell has mitochondria.
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ta_03_14 Evolution of the eukaryotic cell
Slide number: 6
aerobic
bacterium
plasma membrane
spirochete
Animal cell has a flagellum.
endoplasmic
reticulum
nucleus
nuclear
envelope
cyanobacterium
Cell has a nucleus
and other organelles.
Cell has mitochondria.
Plant cell has chloroplasts.
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Cell Differentiation
Cell specialization occurs during the development
of a multi-cellular organism.
 The genetic information necessary for all cellular
functions remains in each cell but may not be
used.

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