Transcript Cells - hrsbstaff.ednet.ns.ca

Cells Made Simple
Biology 11
Ms. Bowie
Cells
• Smallest living unit
• Most are microscopic
Principles of Cell Theory
• All living things are made of cells
• Smallest living unit of structure and
function of all organisms is the cell
• All cells arise from preexisting cells
(goodbye spontaneous generation)
Cell Size
Cells Have Large Surface
Area-to-Volume Ratio
Characteristics of All Cells
•
•
•
•
A surrounding membrane
Protoplasm – cell contents in thick fluid
Organelles – structures for cell function
Control center with DNA
Cell Types
There are 2 main types of cells
• Prokaryotic
• Eukaryotic
Prokaryotic Cells
• First cell type on earth
• Cell type of Bacteria and Archaea
Prokaryotic Cells
• No membrane bound nucleus
• Nucleoid = region of DNA concentration
• Organelles lack membranes too
Eukaryotic Cells
• Nucleus bound by membrane
• Include fungi, protists, plant, and
animal cells
• They contain many organelles
Protozoan
Representative Animal Cell
Representative Plant Cell
Organelles
• Carry out all cellular functions
Plasma Cell Membrane
• Holds all contents of the cell inside
• Controls what enters & leaves the cell
• Structure is a lipid bilayer
Phospholipids
• The membrane parts are “polar”.
– Hydrophylic (water loving) head
– Hydrophobic (water fearing) tail
Movement Across the Plasma Membrane
• A few molecules move freely across the
membrane. They are:
– Water, Carbon dioxide, Ammonia, Oxygen
• Carrier proteins must help other substances
cross the membrane:
– The Proteins are embedded in lipid bilayer
Cell Walls
• Found in plants, fungi, & many protists
• The cell wall is missing in animal cells
• Surrounds plasma membrane
Cell Wall Differences
• Plants – made mostly of cellulose
• Fungi – made mostly of chitin
Cytoplasm
• A thick fluid containing the organelles
• The cytoplasm holds:
–
–
–
–
Interconnected filaments & fibers
Fluid = cytosol
Organelles
storage substances
Cytoskeleton
• Consists of filaments
& fibers
• Made of 3 fiber types
– Microfilaments
– Microtubules
– Intermediate filaments
• 3 functions:
– mechanical support
– anchor organelles
– help move substances
A = actin, IF = intermediate filament, MT = microtubule
Cilia & Flagella
• Provide ability to move
things
• Cilia (hair-like)
– Short
– Used to move substances
outside human cells
• Flagella
– Whip-like extensions
– Found on sperm cells
Centrioles
• Pairs of microtubular structures
• Play a role in cell division (reproduction of
new cell – remember meiosis and
mitosis?)
Membranous Organelles
• Tiny organ found inside cytoplasm
• They are bound by membranes
Nucleus
• Control center of cell
• Double membrane
• Contains
– Chromosomes (DNA)
– Nucleolus
Nuclear Envelope (Membrane)
• Separates nucleus
from rest of cell
• Double membrane
• Has pores just like
the cell membrane.
DNA
• DNA stands for
deoxyribonucleic acid
• The hereditary material
• Holds the entire blueprint
for the organism
• Contained within
chromosomes
Nucleolus
• Most cells have 2 or
more
• Directs synthesis of
RNA
• Creates ribosomes
Endoplasmic Reticulum
• Helps move substances within cells
• It’s a Network of interconnected
membranes
• Two types exist in cells:
– Rough endoplasmic reticulum
– Smooth endoplasmic reticulum
Rough Endoplasmic Reticulum
• Ribosomes attached to surface
– They make proteins
– Not all ribosomes attach to rough ER
• May modify proteins from ribosomes
Smooth Endoplasmic Reticulum
• No attached ribosomes (so it is smooth!)
• Has enzymes that help build molecules:
– Carbohydrates
– Lipids
Golgi Apparatus (or Body)
• Packaging & shipping station of cell
Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi
Golgi Apparatus Function
(Continued)
4. Molecules pinched-off in separate vesicles
5. Vesicle leaves Golgi apparatus
6. Vesicles may combine with plasma
membrane to expel the contents (called
exocytosis)
Lysosomes
• Contain digestive enzymes
• Functions
– Aid in cell renewal
– Break down old cell parts
– Digests invaders
Vacuoles
• Membrane bound storage sacs
• More common in plants than animals
• Holds:
– Water
– Food
– wastes
Mitochondria
• Have their own DNA
• Bound by double membrane
Mitochondria
• Break down fuel molecules (cellular respiration)
– Glucose
– Fatty acids
• Release energy
– ATP
Chloroplasts
• Solar energy capturing organelle
Photosynthesis
• Takes place in the chloroplast
• Makes cellular food – glucose
• Converts sunlight into sugars!
Review of Eukaryotic Cells
Review of Eukaryotic Cells