Cell explanation and structure of cell.ppt

This explains about cell

1. Cell

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Prokaryotic Cells

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Prokaryotic Cells
Prokaryotic cell walls
-protect the cell and maintain cell shape
Bacterial cell walls
-may be composed of peptidoglycan
-may be Gram positive (lots of
peptidoglycan) or Gram negative (small
amount of peptidoglycan)

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Bacteria Cells
Single celled living organisms with a length of
about 1μm
-protect the cell and maintain cell shape
Bacterial cell walls
-may be composed of peptidoglycan
-may be Gram positive (lots of
peptidoglycan) or Gram negative (small
amount of peptidoglycan)

10. Diagram of a bacterium cell
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Eukaryotic Cells

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Eukaryotic Cells

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Eukaryotic Cells

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Eukaryotic Cells
Eukaryotic cells
-possess a membrane-bound nucleus
-are more complex than prokaryotic cells
-compartmentalize many cellular functions
within organelles and the
endomembrane system
-possess a cytoskeleton for support and
to maintain cellular structure

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Eukaryotic Cells
Nucleus
-stores the genetic material of the cell in
the form of multiple, linear chromosomes
-surrounded by a nuclear envelope
composed of 2 phospholipid bilayers
-in chromosomes – DNA is organized with
proteins to form chromatin

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Eukaryotic Cells
Ribosomes
-the site of protein synthesis in the cell
-composed of ribosomal RNA and
proteins
-found within the cytosol of the cytoplasm
and attached to internal membranes

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Endomembrane System
Endomembrane system
-a series of membranes throughout the
cytoplasm
-divides cell into compartments where
different cellular functions occur
1. endoplasmic reticulum
2. Golgi apparatus
3. lysosomes

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Endomembrane System
Rough endoplasmic reticulum (RER)
-membranes that create a network of
channels throughout the cytoplasm
-attachment of ribosomes to the
membrane gives a rough appearance
-synthesis of proteins to be secreted, sent
to lysosomes or plasma membrane

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Endomembrane System
Smooth endoplasmic reticulum (SER)
-functions:
-synthesis of membrane lipids
-calcium storage
-detoxification of foreign substances

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Endomembrane System

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Endomembrane System
Golgi apparatus
-flattened stacks of interconnected
membranes
-packaging and distribution of materials to
different parts of the cell
-synthesis of cell wall components

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Endomembrane System
Lysosomes
-membrane bound vesicles containing
digestive enzymes to break down
macromolecules
-destroy cells or foreign matter that the cell
has engulfed by phagocytosis

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Endomembrane System
Microbodies
-membrane bound vesicles
-contain enzymes
-not part of the endomembrane system
-peroxisomes contain oxidative enzymes
and catalase

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Endomembrane System
Vacuoles
-membrane-bound structures with various
functions depending on the cell type
There are different types of vacuoles:
-central vacuole in plant cells
-contractile vacuole of some protists
-vacuoles for storage

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Mitochondria
Mitochondria
-organelles present in all types of
eukaryotic cells
-contain oxidative metabolism enzymes for
transferring the energy within
macromolecules to ATP (AKA: Cellular
Respiration)
-found in all types of eukaryotic cells

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Mitochondria
-surrounded by 2 membranes
-smooth outer membrane
-folded inner membrane with layers
called cristae
-matrix is within the inner membrane
-intermembrane space is located
between the two membranes
-contain their own DNA – mtDNA –
maternally inherited – circular plasmid

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Mitochondria

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Chloroplasts
Chloroplasts
-organelles present in cells of plants and
some other eukaryotes
-contain chlorophyll for photosynthesis
-surrounded by 2 membranes
-thylakoids are membranous sacs within
the inner membrane
-grana are stacks of thylakoids
- also have own DNA – circular plasmid

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Chloroplasts

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Mitochondria & Chloroplasts
Endosymbiosis
-proposal that eukaryotic organelles
evolved through a symbiotic relationship
-one cell engulfed a second cell and a
symbiotic relationship developed
-mitochondria and chloroplasts are thought
to have evolved this way

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Mitochondria & Chloroplasts
Much evidence supports this endosymbiosis
theory.
Mitochondria and chloroplasts:
-have 2 membranes
-possess DNA and ribosomes
-are about the size of a prokaryotic cell
-divide by a process similar to bacteria

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Mitochondria & Chloroplasts

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Cytoskeleton
Cytoskeleton
-network of protein fibers found in all
eukaryotic cells
-supports the shape of the cell
-keeps organelles in fixed locations
-helps move materials within the cell

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Cytoskeleton
Cytoskeleton fibers include
-actin filaments – responsible for cellular
contractions, crawling, “pinching”
-microtubules – provide organization to the
cell and move materials within the cell
-intermediate filaments – provide structural
stability

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Cytoskeleton

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41. Specialized cell
A cell can carry out many functions like feeding, respiration,
excretion and reproduction.
•Fat cells
they have a small amount of cytoplasm and large amount of
fat.
they have few mitochondria
they can expand (up to 1000 times)
•Cone cells
outer segment
middle segment
last part
•Root hair cells
•Sperm cells

42. Specialized cell

43. Specialized cell

44. Specialized cell

45. Summary Questions
1.Muscle cells can contract (shorten) and are used to
move the body around and also to move substances
around your body. Muscle cells usually contain many
mitochondria. Explain why this is an important
adaptation.
2.The palisade cells are found near the top surface of a
leaf. They contain many chloroplasts. Why is this an
important adaptation?
3.Which part of plant transport water and mineral salts?
4.Which part of the plant transport manufactured food?

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Tissue
This is a group of cells with similar structure and
function working together.
Muscular tissues
Glandular tissue
Epithelial tissue
Epidermal tissue – xylem and phloem

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Organs
They are made of tissues.
Eg. Stomach contains muscular tissue, to churn the food.
Grandular tissues to produce the digestive juice and
epithelial tissue, which covers the inside and the outside
of the organ
Pancreas – pancreatic juice and hormone production
Plant organs: leaves, stems and roots.

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Organ System
An organism is made of organ systems working together.
Organ system is a group of organs that work together to
perform a particular function.
Example: Digestive system

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Excercise
1.What is a tissue?
2.What is an organ?
3.State whether each of the following is a specialized cell,
a tissue, or an organ and explain your answers.
a. sperm
b. kidney
c. stomach
3. Explain how the stomach is adapted for its role in the
digestion of food.