Transcript Cell Structure and Function - Mediapolis Community School

Cell Structure and Function
History of Cell Biology
• The discovery of cells
– All living things are made up of one or more cells
– Cells carry out all the processes of life
• Robert Hooke
– Nature with light microscope
– Cork bark from oak tree
• observed little boxes reminded
him of monk quarters
• Leeuwenhoek
– First to observe living cells
from microscope
– 10 X of Hooke’s instruments
Cell Theory
150 years after the discovery of cells
1. All living organisms are made of one or more
cells
2. Cells are the basic units of structure and
function in an organism
3. Cell come only from the reproduction of
existing cells
Introduction to Cells
Cell diversity
• Variety of shapes and sizes
• Form follows function
Cell Size
• Size varies
• Limited by the relationship of the cell’s outer
surface area to its volume
– Surface area : volume ratio
• Too small of surface area compared to volume
of the cell
– Material would not enter or leave cell quickly
enough
Basic Parts of a Cell
• Plasma membrane (cell membrane)
– Barrier between inside and outside of cell
• Cytoplasm
– Cytoskeleton, organelles, fluid
• DNA
– Regulating functions and reproduction
• Ribosomes
– Help in the production of Proteins
Two Cells Types
• Prokaryotes
• Eukaryotes
Prokaryotes
• Lack membrane – bound organelles
• Have genetic information
• Bacteria and Archea
Eukaryotes
• One or more cells
• Have nucleus and organelles
– Membrane bound structures that perform
specific functions
Cell Membrane and Organelles
• Cell membrane
– Semi – permeable
– Phospholipid bilayer
– Polar hydrophilic (water – loving) head
– Point outward/inward towards water
• 2 nonpolar hydrophobic (water – fearing) fatty acid tails
– Tails point inward away from the water
– Animal cells also have sterols (type of lipid)
• Firm membrane and prevents freezing
Membrane Proteins
Found within the lipid bilayer
• Cell – surface marker
– Glycoprotein identifies cell
• Receptor protein
– Recognizes and binds substances outside of cell
• Transport protein
– Helps substances move across the membrane
• Enzyme
– Assists in chemical reaction inside the cell
Cytoskeleton
• Thin tubules and filaments in cytosol
– Microtubules
• Maintain cell shape
– Microfilaments
• Cell movement
– Intermediate
• Anchor organelles
• Cilia and Flagella
• Centrioles
Nucleus
• Nuclear envelope
– Nucleolus
• Ribosomes
– made of RNA and aids in
protein synthesis
Mitochondria
• Transfer energy from organic molecules to
make ATP
• 2 membranes
– Outer
– Inner (site of energy production)
• mDNA
– More mDNA can be made only from mitochondria
• Endosymbiosis
Ribosomes
• Non – membrane bound organelle made of
RNA and proteins
• Builds protein
• Free or attached to endoplasmic reticulum
Endoplasmic Reticulum
• Intercellular highway of tubes and sacs
• Two types
– Rough ER
• Covered with ribosomes
• Produces phospholipids and
proteins
– Smooth ER
• Not found in abundance
• Build lipids and steriods
• Help detoxify
Golgi Apparatus
• Receive vesicles from ER containing proteins
• Modify received material and tag it for
delivery
Vesicles
• Small spherical sac made of a single cell
membrane
• Migrate and merge with cell membrane
• 3 types of vesicles
– Lysosomes (digestive enzymes)
– Peroxisomes (abundant in liver and kidney cells)
– Contractile vacuole (plant cells hold excess water)
Protein Synthesis
1. Assembled by ribosomes on the Rough ER
2. Vesicles transport proteins to the Golgi
Apparatus
3. Golgi modifies proteins and packages them in
vesicles
4. Vesicles release proteins outside of the cell
Plant Cells
• Cell walls
– Rigid layer outside of cell membrane
• Central vacuoles
• Plastids
– chloroplast
• Photosynthesis
• endosymbiosis
– Other contain pigments and starch storage