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HOMEWORK!
• READ & TAKE NOTES ON
Chapter 3.1-3.3
• Turn in your macromolecules lab
– Fill out a yellow sheet if you don’t have it!
We are beginning Ch.3
• Watch the “Introducing the Cell” video segment
(19:13)
• Cells are too small to be seen w/ the
naked eye. So how can you see a cell?
_______________________________
Who was the 1st to ID cells?
• mid 1600s scientists begin to use microscopes
• 1665 Robert Hooke used early version cmpd
microscope to view a thin slice of cork.
– He called what he saw “cells,” b/c it reminded him of
the monastery’s tiny rooms, which they called cells.
there are several types of microscope:
• cmpd light microscope- allows light to pass thru
a specimen & 2 lenses form an image
-used to view dead orgs, tiny live orgs, live
cells;
-dyes can be used to make images better
• electron microscope- used to view objects much
smaller than size of cell (for ex: cell organelles), it
uses beams of e-’s to view images
2 types of e- microscope:
TEM  shine beam of e-’s thru specimen
reveal lots of detail inside cell
SEM  scan narrow beam of e-’s back & forth
across specimen surface produce
realistic often 3-D images of specimen
surface
*cannot see live specimens w/either type b/c they must
be preserved & dehydrated before they can be viewed
using either microscope
New Class of Microscope!
• 1990s scanning probe microscopes were
perfected
-a fine probe traces the surfaces of
samples
-the probe is similar to the needle on
turntable that plays records
-the force of the probe is so slight it
usually causes no damage to the
specimen
The Cell Theory
• several basic ideas from diff scientists were combined to
create the cell theory:
– All living things are composed of cells.
– Cells are the basic units of structure & function
for all living things.
– New cells are produced from existing cells.
Prokaryotes vs. Eukaryotes
• Prokaryotes
• DNA not contained in a
nucleus
• Generally less
complicated
• Single-celled
• Eukaryotes
• DNA contained in a
nucleus
• Nucleus separated from
other organelles
• Great variety of
organisms
• Can be single or multicellular
• inside of each eukaryotic cell, there are little
compartments called organelles (literally “little
organs”) that have a special job to do
• talk about the cell in terms of nucleus, & everything
outside of the nucleus
• cytoplasm - the space outside the nucleus
where all the other organelles are housed
nucleus (control center of the cell)
-contains the DNA which has
the coded instructions for
how to make proteins &
other molecs
-several parts:
-nuclear envelope - dotted w/
lots of pores so that
material can move in & out
-chromatin – DNA spread out
& attached to proteins; when
cell divides it will condense to
form chromosomes
-nucleolus – where assembly of
ribosomes begins
Ribosomes
•
•
•
•
•
Proteins are assembled on the ribosomes
They get their instructions from… ____________________
Made of RNA & protein
Found throughout the cytoplasm or attached to the ER
Where are ribosomes assembled? ____________________
Endoplasmic Reticulum (ER)
• An internal membrane
system
• rough endoplasmic
reticulum (RER)
• Ribosomes are attached
(rough)
• Where proteins are made by
the ribosomes, then chemically
modified
• smooth endoplasmic
reticulum (SER)
• enzymes perform special tasks
• Making lipid parts of cell membrane
• Detoxifying drugs
Golgi Apparatus (Golgi Body)
• looks like a purse/sack
• modifies, sorts, & packages
proteins & other materials
from ER
• then stores them or secretes
them into cell or out of cell
wherever needed
Lysosomes
• small, round organelles filled w/ enzymes
• job is to digest / breakdown lips, carbs,
proteins, organelles that are no longer useful
into smaller molecules that can be reused by
the rest of the cell
• if not for the membrane, the contents of the
lysosome would destroy the cell!
• several serious human diseases linked to
malfunctioning lysosomes
Peroxisomes
• small memb-enclosed organelles that
contain enzymes to break down a variety
of things via oxidative rxns
– for ex: it breaks down H2O2 which is
toxic to the cell via catalase;
– it also breaks down uric acid, amino
acids, & fatty acids
Vacuoles
• looks like irregular circle
• stores things like H2O, salts,
proteins, carbs
• in plant cells, it is large enough to
help support heavy structures
like leaves & flowers
mitochondria
-inner membrane folded inside
an outer membrane
-convert chemical E from food into
compounds cells can use
-contains its own small DNA
molecules
-interesting human fact:
most of mitochondria are inherited
from the cytoplasm of the
ovum/egg cell
chloroplasts
-look a lot like mitos
-capture sunlight & create chemical
E via process called
____________________
-contain green pigment chlorophyll,
which gives plants color
-only available in whom?
____________________
-also contains its own small DNA
molecs
plastids
- occur only in plant cells or cells capable of photosynthesis
- leucoplasts (a.k.a amyloplasts) = store starch, as well as
sometimes protein or oils
-chromoplasts = store pigments assoc’d w/ the bright colors
of flowers and/or fruits.
cytoskeleton (structure & transportation system)
-network of prot filaments that help cell maintain its
shape, also involved in movement of material
throughout cell
microfilament = threadlike, made of prot called actin;
tough, flexible frame for support & help cells move
microtubules = hollow, made of prot called tubulin;
-help cell maintain shape;
-also impt in cell ÷ion b/c form spindle which
separates the c’somes;
-also in animal cells forms centrioles which
organize cell ÷ion
-help form cilia & flagella which are
projections enable cell to “swim” thru fluids
Who am I?
What do I do?
Who am I?
What do I do?
Who am I?
What do I do?
I haven’t looked like this to you before….but this
is what I really look like
Did you know that lysosomes come from
the golgi body?
Who am I?
What do I do?
a few more things about chloroplasts
-filled w/ chlorophyll
-stacks of membranes called thylakoids
-thylakoids submerged w/in fluid called
stroma
Credits…….
previous pictures from various
websites….& good bit of info &
some pictures from:
http://www.emc.maricopa.edu/faculty/farabee/B
IOBK/BioBookCELL2.html
Homework
• Read and answer the questions on pg. 80
– Put your answers and any notes you take in the
warm-up section of your notebook
Can you tell the diff btwn an animal & plant cell?
Picture below from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
The cell wall is composed of cellulose, which gives us
fiber!
Vacuole
Smooth endoplasmic
reticulum
Ribosome
(free)
Chloroplast
Cell
Membrane
Ribosome
(attached)
Nuclear
envelope
Cell wall
Nucleolus
Golgi apparatus
Mitochondrion
Nucleus
Rough endoplasmic reticulum
On to Section 3
•The cell membrane is a phospholipid bilayer.
What does that mean?
picture below from http://library.thinkquest.org/C004535/cell_membranes.html
Picture below from:
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%2010
1%20Lectures/Membranes/membrane.htm
GREAT SITE!
So what does the bilayer act like?
• …kind of like a fluid (i.e. film of oil on H2O)
– The cell membrane is flexible
– The phospholipids can move around and go past
one another in a layer
• But only side to side, no somersaults for the embedded
proteins
• We call this the “fluid mosaic model”
Selective Permeability
• A property of the cell membrane
• Allows some materials to cross
• Aka: semipermeable and selectively
permeable
• Helps maintain homeostasis
– Why is that important?
Molecule Movement
• Some methods require energy, some don’t
• Small, nonpolar: go through the membrane
easily
• Small, polar: transported via proteins
• Large: moved in vesicles
Chemical signals are transmitted
across the cell membrane
• Receptor: a protein that detects a signal
molecule and performs an action as a
response
– Recognizes and binds to only certain molecules
– The molecule that attaches to it = ligand
– When they bind, they change shape
Intracellular Receptor
• Intra=inside/within
• Molecule must first be able to cross the
membrane, like…………
– Small, nonpolar
– Ex. Many hormones
• An effect is only seen if there is a specific
receptor
Ex. of Intracell. Recpt.
• Aldosterone enters a kidney cell
– Binds to an intracell. Recpt.
• Receptor-ligand complex enters the nucleus
– Interacts w/ the DNA
– Turns on certain genes
• Result: specific proteins are made that help
the kidneys absorb sodium ions and retain
water
Membrane Receptor
• If molec cannot cross membrane, it can bind
to a receptor in the membrane
• The entire recptor changes shape
– Molecs inside the cell respond
Diffusion
• diffusion =
• 2 maj types of diffusion:
– passive diffusion  does not require E
– active diffusion  requires E
• Conc. Gradient: the diff in the conc of a
substance from one place to another
– High -> low
Diffusion & Osmosis
if diffusion = movement from area of high
conc to an area of low conc
• osmosis = movement of H20 from area
of hi to lo conc
Types of Osmosis (refer to Fig 3.23):
isotonic soln  equal conc
hypotonic soln  filled w/ H2O (about to
burst). Soln has less solutes
hypertonic soln  losing H2O (shriveled)
Facilitated Diffusion
facilitated diffusion = when a prot helps a
molec, like gluc, move across a memb
It does not require E!
Still moving down the conc gradient.
Transport Proteins
• Some are simple channels, or tunnels
• Others act like enzymes
– When bound, the prot changes shape
• Molec travels the rest of the way
Facilitated Diffusion
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
Figure 7-15 Osmosis
Section 7-3
Active Transport
active transport = movement across a memb
that requires E b/c it is going against the normal
movement of particles
Proteins use E
2 types:
endocytosis 
phagocytosis  (“cell eating”) pkg it w/in a
food vacuole & engulf it
pinocytosis  tiny pkgs filled w/ liquid
exocytosis 
Active Transport
Section 7-3
Molecule to
be carried
Energy
Molecule
being carried
Review Parts of the Cell
• Is it true that prokaryotes don’t have DNA?
• Which organelle incorporates the lipids into the
membrane?
• Which organelle breaks down peroxide?
• What is the path that proteins take?
• What part of the cytoskeleton is involved in mitosis
and makes up cilia and flagella?
• Which organelle stores pigment?
• Which organelle converts chemical energy to ATP?
Review the Cell Membrane
• What phrases should be used to describe the cell
membrane?
• What are the parts of the membrane?
-What are the functions of each part?
Review the Types of Diffusion
• What are the 2 major types of diffusion?
-What is the difference between the 2 major types?
• What are the types of passive diffusion?
• What are the types of active diffusion?
•What are the types of osmosis?
What do diff cells look like?
Adipocytes = fat cells
Erythrocytes as seem with the SEM. The bottom image is human red blood cells, platelets
and T-lymphocyte (erythrocytes = red; platelets = yellow; T-lymphocyte = light green)
(SEM x 9,900). This image is copyright Dennis Kunkel at www.DennisKunkel.com, used
with permission.
Levels
of Organization
So you see
why
the levels of biological
organization work?
Section 7-4
Muscle cell
Smooth muscle tissue
Stomach
Digestive system
HOMEWORK!
Review your notes!
Finish any unfinished note-taking
from last class.