Transcript cells - MrMsciences

Chapter 7
A view of the cell
The History of the Cell Theory (p 172)
•Compound Light microscopes
•Invented by Anton van Leeuwenhoek
•1500 x
•Electron microscopes
•Scanning electron microscope (SEM,扫描电镜)
•Surface of 3D objects
•Transmission electron microscope (TEM, 透射电镜)
•Inside a cell
•Scanning Tunneling microscope (STM)
•Viewing atoms
The History of the Cell Theory (p172)
Robert Hooke- first to use the word “cells”
The Cell Theory:
1. All organisms are composed of one or more cells.
2. The cell is the basic unit of structure and
organization of organisms.
3. All cells come from preexisting cells.
Two Basic Cell Types (p173)
Prokaryotes （原核生物):
Cells that do not contain any
membrane- bound organelles
Most unicellular (one cell) organisms;
bacteria
Two Basic Cell Types (p173)
Eukaryotes (真核生物):
Cells that do contain membranebound organelles
Most multicellular (many cells) organisms;
plants, animals, etc.
Some unicellular organism too; algae
Prokaryote Vs. Eukaryote
Prokaryote
Eukaryote
No membrane-bound
organelles
Membrane-bound
organelles
No nucleus
Nucleus
Small (0.001-0.01 mm)
Large (0.01-0.1mm)
Small Ribosomes
Large Ribosomes
Small, normally circular
DNA
Large, chromosome DNA
Maintaining a Homeostasis (p175)
Homeostasis- stable state of a healthy functioning cell
Plasma Membrane- “guard” of the cell; first step
towards homeostasis
Selective permeability (选择透过性)- a process in which
a membrane allows some molecules to pass through
while keeping others out.
Transport proteins- special tunnels or doors that only let
in specific molecules
Structure of the Plasma Membrane (p177)
Phospholipidshydrophilic heads
and hydrophobic
tails make a
double layered
wall
Cholesterol- help keep membrane
fluid and stable
Carbohydrates- used in cell
communication
Structure of the Plasma Membrane
Fluid Mosaic Model
Cell Organelles
Organelles- “tiny organs” inside the cell
• have a specific job to maintain
homeostasis (healthy cell)
• Some are in all cells; membrane
• Some are only found in either
animal or plant cells
Cellular Boundaries
Animal Cell:
Plasma membrane
Plant Cell: Plasma membrane and Cell wall (cellulose)
The Nucleus (细胞核)
The “brain” of the cell; contains DNA (Chromatin)
Making proteins!
Ribosomes- take copy of DNA’s information (mRNA) and use
it as a guide to create proteins
Endoplasmic Reticulum- site of chemical reactions inside cell
Smooth ER- no ribosomes
Rough ER- ribosomes
Transportation Center
Golgi Apparatus- puts proteins into small membrane-bound
packages called vesicles which are sent
out and around the cell
Vacuoles- storage compartments for food, enzymes, etc.
In plant cells- they are very large and hold lots of water
In animal cells- very small; transport things inside the
cell
Vacuoles
Cellular Digestion
Lysosomes- sacs of
digestive enzymes that
break down old
organelles, food, and
viruses/bacteria
Making Energy in Plant Cells (p184)
Chloroplasts- perform photosynthesis to make energy from
sunlight in planets and some unicellular
organisms
Chlorophyll- chemical that absorbs wavelengths of sunlight,
expect green
Making Energy in Animal Cells (p185)
Mitochondria- “power house” of the cell; produces
ATP(energy unit for cells) by
breaking down sugars and other
organic compounds
(cellular respiration)
Organelles for Support (p 185)
Cytoplasm- clear gel-like fluid inside cells; help holds
organelles in place
Cytoskeleton- “Bones” of the cell; crossing rods, filaments,
and
tubes, that hold the cells shape. Also act at a
“railroad” system to move things around the cell
The Cytoskeleton
Organelles for Support
Centrosome- move
chromosomes during
cell division in
animal cells
Locomotion
Flagella- long, wipe-like tail that
pushes and rolls the cell
Cilia- short, hair-like paddles that
push the cell along
Animal Cells Vs. Plant Cells
Organelle
Plants only
Animals only
Plasma
Membrane
Cell Wall
Both
X
X
Nucleus
X
Ribosomes
X
Endoplasmic
Reticulum
X
Gogi Apparatus
X
Lysosome
X
Vacuole
(large)
Centrioles
X
X
Mitochondria
Chloroplasts
(small)
X
X
Tour of an Animal Cell
Tour of an Plant Cell
P 192
Homework
• Cell labeling practice sheet
Cellular Transport
• Cells must move things inside and
outside to maintain homeostasis
• What might they need to take in:
– Food molecules
– Signals
– Ions
• What might they need to release:
– Waste material
– Proteins
– Signals
Cellular Transport
• 2 Types of transport:
1) Passive Transport
– Does not require the cell to use
energy to move
2) Active Transport
– Does require the cell to use
energy
– Cell uses energy units (ATP)
Passive Transport: Diffusion
• Diffusion movement of molecules from
areas High concentrations to areas of Low
concentrations; down a concentration
gradient
• Food coloring in water, sugar in water, fart
fills a room, etc…
• Where does the energy come from for this
movement?
– Kinetic energy in molecules (random
movement)
Passive Transport: Facilitated
Diffusion
• Facilitated diffusion diffusion through a
protein channel or carrier protein that is
specific for 1 type of substance (Na+, Cl-,
glucose, etc…)
• Still follow concentration gradient
• Can become saturated meaning the
movement is at its maximum rate and can
not go any faster
Passive Transport: Osmosis
• The diffusion of water across a
selectively permeable membrane（选择
性透过膜） is called osmosis(渗透)
• H2O is small enough to fit between
phospholipids but moves very slow, why?
– Hydrophobic center of membrane
pushes it back
• Aquaporins transport channels just for
H2 O
Osmotic Pressure:
• Movement of water can increase and
decrease pressure inside the cell
• Hypotonic Solution
– concentration of solute is low (high H2O) on the
outside and high (low H2O) on the inside of the cell
– Water moves into the cell causes it to swell
Osmotic Pressure
• Hypertonic Solution
– concentration is high (low H2O) on the
outside and low (high H2O) on the inside
– Water rushes out of the cell causing it to
shrink
Osmotic Pressure
• Isotonic solution
– concentration inside and outside the cell
are equal (equilibrium)
– Movement of water in and out of the cell is
at equal rates; best for animal cells
Active Transport
• Energy is required to move molecules
AGAINST their concentration gradients
• ATP must be used to make carrier proteins
(pumps) move molecules to the other side
• Cell uses active transport to create
concentration gradients to be used later by
passive transport; nervous system
Active Transport: Large Particles
• Endocytosis
– Cell folds around large particle and pulls
it in; plasma membrane makes vacuole
• Exocytosis
– Vacuole fuses with plasma membrane
and release large particles
Know The Difference!
Homeostasis: Happy Cells
• All strive to maintain homeostasis
• In single-celled organisms this is not
very difficult
• In multi-celled, complex organisms
there are many methods used:
• Cell specialization
• cells for different organs that do
different jobs
• Cell Communication
• systems talk to each other
• Organized levels
CellsTissueOrgan System
Homework
• Read Ch. 8 and do Ch. 8
Vocabulary
• Ch. 7 Apply Vocabulary and
Questions #1-18 on p.187188