Transcript Cells - Midway ISD

Cell Structure and Function
Chapter 7
7-1 I.
Life is Cellular
A. Discovery of the Cell
1. Robert Hooke
a. 1665 used simple microscope to look at
thin layer of cork
b. called them empty “chambers” or “cells”
2. Anton Van Leeuwenhoek
a. used single lens microscope to observe
pond water
b. found a new world of living things
Cells- the basic units of life
 Cell Theory –
a. all living things are composed of cells
b. cells are the basic units of structure
and function in living things
c. new cells are produced from existing
cells
B. Exploring the Cell
1. Compound Light Microscope
a. More than one lens or objective
b. Uses a light source
2. Electron Microscope
a. 1000x as powerful as a light microscope
sends beams of electrons through specimen
3. SEM’s (scanning electron microscope)
a. produces 3-D images electrons scan surface
of object
4. Confocal Light Microscope
a. scans cells with laser beam
C.
Prokaryotes vs Eukaryotes
NUCLEUS- membrane bound organelle that
contains genetic information (DNA). Also, controls
the cells activities.
1. Prokaryotes:
a.
cells that do not contain a nucleus
b.
no membrane bound organelles
c.
DNA is found within (no specific area)
Example: bacteria
2. Eukaryotes:
a.
cells that contain a nucleus
b.
DNA is found in nucleus has other
membrane bound organelles
Example: animal cell, plant cell
7-2 Eukaryotic Cell Structure
A. Comparing the Cell to a Community
1. The organelles
- Nucleus
- Ribosome
- Endoplasmic Reticulum (smooth or rough)
- Golgi Apparatus
- Lysosome
- Vacuoles
- Mitochondria
- Chloroplasts
- Cytoskeleton
Nucleus
How it connects:
– School House
What it does:
– Controls the cells processes and contains the
hereditary information of DNA
What it is:
– Surrounded by the nuclear envelope which
allows material to move in and out
Also contains:
– Chromatin- consists of DNA bound to proteins
– Nucleolus- where the assembly of the
ribosomes begins
Ribosomes
How it connects:
– Workers
What it does:
– Site of protein assembly
What it is:
– small particles of RNA and protein found
throughout the cytoplasm
Endoplasmic Reticulum
How it connects:
– Assembly line
What it does:
– Site where lipid components of the cell membrane are
assembled for export from the cell
– Rough: synthesis of proteins
– Smooth: synthesis of membrane lipids, detoxification of
drugs using enzymes
What it is:
– Rough: part of the ER that have ribosomes on the
surface; proteins chemically modified
– Smooth: no ribosomes on its surface (found in liver
cells)
Golgi Apparatus
How it connects:
– Packaging center
What it does:
– Modifies, sorts and packages proteins and other
materials from the ER for storage or secretion
What it is:
– A stack of closely apposed membranes
Lysosome
How it connects:
– The trash cleanup crew
What it does:
– Digestion, or breakdown of lipids, carbohydrates,
and proteins into small molecules that can be
used by the rest of the cell
– Also can break down organelles and remove
“junk” from the cell
What it is:
– Small organelles filled with enzymes
Vacuoles
How it connects:
– Storage facility
What it does:
– Store materials such as water, salts, proteins,
and carbohydrates
– In plants, they provide structure to the cells
– In paramecium, they maintain homeostasis
What it is:
– A saclike structure that is often filled with liquid
Mitochondria
How it connects:
– The power company
What it does:
– Convert chemical energy stored in food into
compounds that are usable to cells
What it is:
– Enclosed by two membranes- outer and inner
membrane- the inner is folded up inside
Extra info:
– In humans, they are inherited from the
cytoplasm of the egg
Chloroplasts
How it connects:
– Solar Power Plant
What it does:
– Capture the energy from sunlight and convert
it into chemical energy for photosynthesis
What it is:
– Two membranes- inside there are stacks of
other membranes containing chlorophyll
Cytoskeleton
How it connects:
– Roads, streets and highways
What it does:
– Helps cells maintain shape
– Assists in movement
What it is:
– A network of protein filaments, called
microfilaments and microtubules
Centrioles
How it connects:
– City Planner
What it does:
– Helps organize cell division
What it is:
– Formed by tubulin
7-3 Cell Boundaries
A. Cell membrane
1. regulates what enters and exits the cell
and provides protection
2. made of two layers- phospholipid bilayer
a. phosphate heads (hydrophilic)
b. lipid tails (hydrophobic)
c. proteins
d. cholesterol (a lipid) (helps with
structure)
Figure 8.1 Artificial membranes (cross sections)
Figure 8.2 Two generations of membrane models
Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross section
B. Cell Wall
1. Provides support and protection
2. Made of cellulose
a. carbohydrate fiber (wood and paper is
made from)
3. found in plants, algae, fungi, and many
prokaryotes
4. found on outside of cell membrane
C. Diffusion Through Cell Boundaries
1. Diffusion- movement of molecules across a
membrane
2. Concentration- mass of solute/volume of
solution
a. molecules will move from an area of HIGH
concentration to an area of LOW
concentration
b. molecules will continue to move until
they’re equal
****Diffusion requires NO energy****
Figure 8.11 Osmosis
D.
Osmosis- Diffusion of water through a
selectively permeable membrane (pg 186)
1. Isotonic solution- concentrations of solutes
is the same inside and outside of the
cell
2. Hypertonic solution- solution has a higher
solute count than the inside cell
(cell
shrinks)
3. Hypotonic solution- solution has a lower
solute concentration than the cell
(cell
will balloon up)
4. Osmotic Pressure- pressure that builds up
inside the cell (good and bad)
Figure 8.12 The water balance of living cells
Figure 8.14 Two models for facilitated diffusion
Figure 8.13 The contractile vacuole of Paramecium: an evolutionary adaptation for osmoregulation
Animation How Diffusion Works.mht
How Osmosis Works.mht
E. Active Transport- the process of moving
molecules against the concentration gradient
1. Small molecules are carried across the
membrane by TRANSPORT PROTEINS.
2. Large molecules are actively transported
1 of 2 ways
a. Endocytosis- taking material into cell
by engulfing the membrane
around
the molecule
b. Exocytosis- pushing material out of
cell
****REQUIRES ENERGY****
Figure 8.16 Review: passive and active transport compared
7-4 Diversity of Cellular life
A. Unicellular- organism made of one
cell only
B. Multicellular- organism made of more
than one cell or many
1. Specialized cells- cells that
perform a specific task.
Ex. Red blood cells carry O2
C. Levels of Organization
1.
2.
3.
4.
5.
Cells- basic unit of life
Tissues- a group of similar cells
Organs- a group of tissues
Organ systems- a group of organs
Organisms- a group of organ systems
http://www.zerobio.com/target_practice_qui
z/target_practice_quiz_cells.htm
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ructure.htm