cell structure and function
DESCRIPTION
Cell Structure and Function. Levels of Organization. Organism. Organ System. Organ. Tissues. Organelles. Cells. Cells. A cell is the smallest unit that is capable of performing all 8 life functions . MRS C GREN. Cells. The size & shape of a cell relates to its function. - PowerPoint PPT PresentationTRANSCRIPT
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Levels of Organization
Organism OrganOrgan System
TissuesCellsOrganelles
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Cells A cell is the smallest unit that
is capable of performing all 8 life functions.
MRS C GREN
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Cells The size & shape of a cell
relates to its function.
Two main types of cells:1. Prokaryotic2. Eukaryotic
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Prokaryotic Cells Cells that lack a cell nucleus,
or any other membrane-bound organelles.
Chromosome is a simple DNA chain with the ends joined to form a circle.
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Prokaryotic Cells Most are unicellular, but
some prokaryotes are multicellular.E.g . bacteria, blue-green algae
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Eukaryotic Cells Higher organisms whose cells are
arranged into complex structures enclosed within membranes.
The chromosome is a length of DNA folded. It is wound around proteins.
E.g. Animals, plants, fungi and protists.
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Organelles No plant or animal cells are
alike but they do share some common organelles.
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In your Notes....Organelle Location Features Function
Plant
Animal
Uni
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Cell Membrane All cells are separated from
their environment by a cell membrane.
For cells with cell walls, the membrane is inside the cell wall.
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Cell Membrane Consists of two layers
of lipids (lipid bilayer).
One lipid includes a hydrophilic (water-loving) head and hydrophobic (water-hating) tails.
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Lipid
Lipid Bi-layer
Cell Membrane
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Semi-Permeable Membrane Proteins in the membrane allow
nutrients, oxygen, and water into the cell and waste products out of the cell.
These proteinsalso limit other molecules from entering or leaving the cell.
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Protein Gate
Lipid
Lipid
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Cytoplasm Cytoplasm is the semi-fluid
solution found inside the cells.
It contains dissolved substances, enzymes and all other cell organelles.
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Cytoskeleton Scaffolding-like structure made
of protein found in cytoplasm.
Helps the cell maintain or change its shape.
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Nucleus Usually the largest organelle the
nucleus contains genetic material that directs all cell activities.
Separated from the rest of the cell by a nuclear membrane.
Nucleus
Nucleolus
Pores
Nuclear Membrane
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Nucleus
Made up of three parts:
1. Nuclear envelope – a double membrane covering that controls the entry and exit of the large molecules and particles that need to go in and out.
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Nucleus2. Genetic Material – In a resting
cell the DNA is unravelled (chromatin) and too small to be seen.
When a cell is aboutto divide the DNA coils, thickens and can be seen (chromosomes).
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Nucleus3. Nucleolus – The main function
of the nucleolus is the production and assembly of ribosome components (RNA, proteins).
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Endoplasmic Reticulum (ER) Continuous with the cell
membrane and the nuclear envelope.
The ER is a series of membranes and connecting tubes that provide a work surface for chemical reactions as well as a passageway for moving materials around the cell.
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Endoplasmic Reticulum (ER) There are two types or ER:
1. Smooth ER 2. Rough ER (ribosomes
attached)
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Ribosomes Found either bound to the ER
or free floating within the cytoplasm.
Site where proteins are made (protein synthesis).
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Ribosomes Free ribosomes
make proteins to be used in the cell.
The ribosomes bound to the ER make proteins to be secreted by the cell.
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Golgi Bodies/Apparatus A series of
flattened sacs found in the cytoplasm.
The primary function is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell.
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Lysosomes Tough,
membranous bags containing digestive enzymes.
They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.
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Vacuoles Vacuoles are membrane-bound
compartments that can serve a variety of storage functions.
They often contain water, food or wastes.
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Vacuoles In animal cells food vacuoles engulf
food where it is digested by the lysosome's enzymes.
In plants it acts as a storage, a fluid skeleton and it also hold colour and poisons.
In unicellular organisms contractile vacuoles pump water out of the cells.
Video
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Contractile Vacuoles These specialized vacuoles
pump excess water out of a cell and is found prominently in freshwater protists.
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Mitochondria Converts energy
from food into a form that a cell can use, called ATP.
It is the site of aerobic respiration. A cell with a large energy requirement will have lots of mitochondria.
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Mitochondria It has its own circular DNA, ribosomes
and transfer RNA and protein making machinery.
In the matrix the krebs cycle takes place.
The electron transport chain takes place in the cristae.
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Cell Wall Found in plant cells, algae
and most bacteria.
Made of cellulose to provide strength and shape.
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Chloroplasts Found in the cytoplasm of plants.
Function is to manufacture glucose through photosynthesis.
Contains the green pigment chlorophyll.
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Chloroplasts Made of thylakoid discs
arranged in stacks called grana.
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Centrioles Found in all animal cells and most
unicellular organisms.
During cell division, the centriole pair extends to form spindles to move chromosomes apart.
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Cilia and Flagella Found in some animal cells and
unicellular organisms.
Both are cellular projections and are almost identical in structure, although cilia are shorter and often more numerous.
Many cells that line surfaces within our bodies are ciliated.
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Cilia and Flagella Both are often
associated with movement.
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Eyes Spots Photoreceptive organelle found in
green algae and other unicellular photosynthetic organisms.
It allows the cells to sense light direction and intensity and respond to it by swimming either towards or away from the light.
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Eye Spots This helps the cells in finding an
environment with optimal light conditions for photosynthesis.
Eyespots are the simplest and most common "eyes" found in nature.
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Cilia and Flagella