Transcript Cell Structure

Cell Structure &
Function
Objectives
Discoveries important to the cell theory
State the parts of the cell theory
Identify the limiting factor on cell size
Describe the relationship to cell shape and
function
Differentiate between prokaryotic and
eukaryotic cells
Cell Theory
All living things are composed of cells
Cells are the basic units of structure and
function of an organism
Cells come only from other cells
Diversity
Size: limited by the ratio of volume to
surface area
Shape: depends on the function of the cell
Internal Organization: organelles
Limits to Cell Size
More demands on the cells DNA
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increase in volume means more materials are needed
nucleus must keep up with cell’s needs
volume increase places strain on the nucleus
Trouble moving materials across the cell membrane
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materials have a long way to travel
takes more time to travel farther
cell needs more food and oxygen greater volume
Surface area to volume ratio
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volume increases more rapidly than surface area
surface area must allow needed materials to enter
greater volume requires more materials
Prokaryotic vs. Eukaryotic
Prokaryotic cells are unicellular and lack
organelles and a nucleus
Eukaryotic cells have membrane bound
organelles and nucleus
Eukaryotic Cells
Objectives
Describe the structure and function of the
cell membrane
Name and describe cell organelles by
function
Describe the function of the nucleus
Differentiate between plant and animal cells
Cell Membrane
Selectively Permeable – allows only
substances to cross
Made of phospholipids
• Polar heads
• Non-polar tails
• Form a bilayer (2 layers)
Membrane Proteins
Cell recognition
Cell transportation
Sites of attachment
May be peripheral or integral
Fluid Mosaic Model
Membrane behaves like a fluid
Proteins are free to move
Like beach balls on the surface of water
Organelles
Cytoplasm – gelatin-like substance
between the cell membrane and nucleus
(cytosol)
Mitochondria – site of energy production
(ATP); two layers
• Outer layer – barrier
• Inner layer – called christae
• Has its own DNA
Ribosomes – smallest organelle; important
in protein synthesis; small bits of RNA
Endoplasmic Reticulum – shipping
• RER – has ribosomes attached; makes proteins
for export from the cell
• SER – makes new parts for cell membrane
Golgi Apparatus – modifies proteins;
exports from cells
Lysosomes – digestion and protection
Cytoskeleton – shape and movement
• Mitrotubules – spindle fibers for cell division
• Microfilaments - movement
Cilia and Flagella – movement
• Cilia – short hair-like; many
• Flagella – long whip-like; 1 or 2
Nucleus – cell activities and inheritance
• Nuclear envelope – surrounds (membrane)
• Chromatin – thread-like strands of DNA
• Chromosomes – condensed chromatin for cell
division
• Nucleolus – site of ribosome production
Plant Cells
Cell wall –
• Outside the cell membrane
• Supports and protects
• Made of cellulose
Vacuole – storage for enzymes and wastes
Plastids – similar to mitochondria
• Capture light for photosynthesis (chloroplasts)
• Flattened sacs called thylakoids
(photosynthesis)
Multicellular Organization
Tissues – cells working together
Organ – tissues working together
Organ System – organs working together
Colonial Organization – genetically
identical cells living together
Cell Transportation
PASSIVE
• Osmosis
• Diffusion
• Filtration
Active
• Exocytosis
• Endocytosis
Phagocytosis
Pinocytosis
Ion Pumps
DNA
Deoxyribose
Double Helix
Nitrogenous Bases
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Adenine
Cytosine
Guanine
Thymine
Protein Synthesis
Replication -
DNA makes a copy of
itself
Transcription -
DNA template used to
make RNA
Translation -
RNA moves to
cytoplasm to make
protein
Cell Division: Mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Parts of a Cell
Structure
Plasma Membrane
Ribosomes
Endoplasmic Reticulum
Smooth ER
Rough ER
Mitochondria
Lysosomes
Centrioles
Golgi Apparatus
Nucleus
Cilia / Flagella
Function
Protection
Make protein
Makes lipids / carbohydrates
Transports proteins
Energy (ATP)
Digestive enzymes
Cell division
Packages from ER
Heredity / Metabolism
Movement