Download Cellular Structures

Cytology
The study of cells
Cell Types
1) Procaryotic
2) Eucaryotic
Procaryotic Cells
Cells lack a true nucleus
Cells have only non-membrane bound
organelles
Bacteria and some algae
Eucaryotic Cells
Cells have a true nuclues
Cells have membrane bound organelles
Most protists
All fungi, plants, animals, and humans
Cellular
Structures
1) Boundary
2) Cytoplasm
3) Nucleus
Cellular Boundaries
Plasma membrane
Cell wall
Middle lamella
Capsule / sheath / slime coat
Plasma membrane
The outermost boundary of all cells
Semi-permeable
Phospholipid bilayer
Proteins are embedded within
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transportation
cell recognition
cell adhesion
Plasma membrane
LAMININ VIDEO CLIP BY
LOUIE GIGLIO
Cell wall
Rigid structure surrounding some cells
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all procaryotes
plants, algae, fungi, and protozoans
Porous
Composed of cellulose or chitin
Middle lamella
Layer between two adjacent cell walls
Acts as a lubricant
Capsule / Sheath / Slime coat
A cellular secretion of polysaccharides
Surrounds unicellular or colonial
organisms
Protective
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Attackers must first dissolve the capsule or
penetrate it
Cytoplasmic Organelles
Cytoplasmic matrix
Ribosomes
Endoplasmic
reticulum
Mitochondria
Plastids
Golgi body
Lysosomes
Vacuoles
Centrioles
Flagellum
Cilia
Cytoplasmic Matrix
(aka: the cytoplasm)
Located in all types of cells
A semi-solid watery substance in which all
other organelles are suspended
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Think “jello salad”
Provides structure to the cell thanks to its
cytoskeleton
Cytoplasmic streaming – contents are
always moving
Ribosome
Located in all types of
cells
Mass of proteins and
RNA
Function: protein
synthesis
Endoplasmic Reticulum
Seen only in eukaryotic cells
Folds of cellular membranes
Continuous with both the plasma
membrane and the nuclear membrane
Functions:
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Provide flexible but structural shape
Synthesis of proteins, lipids, &
polysaccharides
Movement of substances throughout the cell
Types of ER’s
Mitochondria
Seen only in eukaryotic cells
A double-membrane bound bean shape
structure
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Inner membrane is folded to form cristae
Function: cellular respiration
Quantity is dependent on the activity level
of the cell
Mitochondria
Plastids
Seen only in plants and algae
A double-membrane bound structure
Function: synthesis and storage of
polysaccharides
Types of Plastids
Chromoplasts
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Contains the pigments used in synthesizing
polysaccharides
Given specific names based on the type of
pigment in the chromoplast
Most important chromoplast: the chloroplast
(green pigment)
Chloroplast
Inner membrane is folded to form the thylakoid
Stack of thylakoids is called a grana
Fluid within the chloroplast is called stroma
Types of Plastids
Leucoplasts
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Colorless structure
Function: a storehouse
of starch
Most numerous in the
fleshy, storage areas
of plants
Golgi body
Seen only in
eukaryotic cells
A flat, curved,
membrane structure
Function:
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Synthesizing
polysaccharides
Final modifications of
proteins & lipids for
their final destination
Lysosome
Seen only in eukaryotic
cells
Small, membrane bound
spherical structure
Contains digestive
enzymes
Function:
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digestion of old, used
organelles
digestion of invading cells
Vacuoles
Seen only in eukaryotic cells
Function: storage
4 types of vacuoles
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Phagocytic
Pinocytic
Waste
Contractile
Types of Vacuoles
Phagocytic
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Storage of food
Formed by phagocytosis
Pinocytic
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Storage of water
Formed by pinocytosis
Waste
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Storage of nondigestible material
Fuses with the plasma membrane to release material
Types of Vacuoles
Contractile vacuole
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Found in unicellular
organisms that live in
a freshwater
environment
Collects excess water
and pushes the water
back out of the cell
Centriole
Seen only in
eukaryotic cells,
except plants
2 cylinders occurring
at right angles to each
other
Always located near
the nucleus
Function: cell division
Flagellum
Located in all types of cells
Long, tubular extension of the
cytoskeleton within the cytoplasm
Small quantity: usually have 1 – 4 flagella
on a cell
Function: locomotion of the cell
Cilia
Located in all types of cells
Short extensions of the cytoskeleton
Usually covers the entire cell or a large
section of a cell
Function: locomotion of the cell or
movement of substances within an
organism
Internal Structure of Cilia & Flagella
Both have the same internal structures
Both structures have been used to disprove
evolution
Irreducibly complex
Nucleus
(the control center of the cell)
Nuclear envelope
Chromatin material
Nucleolus
Nuclear Envelope
Seen only in eukaryotic cells
Porous
Phospholipid bilayer
Continuous with the endoplasmic
reticulum
Chromatin Material
Seen in all types of cells
Long, thin strands consisting of DNA and
proteins
Function: codes for the information
needed for protein synthesis
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DNA permits activity of a cell, but it does not
decide what the cell is capable of doing
DNA was programmed by God at creation
Nucleolus
An area with a large
concentration of RNA
(a substance similar
to DNA)
Review of Cellular
Structures