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/ thenaked 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 multi-

cellular

• 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 nucleuswhere 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

- 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.

plastids

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 variouswebsites….& good bit of info &

some pictures from:

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/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

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

The cell wall is composed of cellulose, which gives us fiber!

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%20101%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 & Osmosisif 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 conchypotonic soln filled w/ H2O (about to

burst). Soln has less soluteshypertonic soln losing H2O (shriveled)

Facilitated Diffusion

facilitated diffusion = when a prot helps amolec, 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

Glucosemolecules

Proteinchannel

HighConcentration

CellMembrane

LowConcentration

Facilitated Diffusion

Section 7-3

Figure 7-15 Osmosis

Active Transportactive transport = movement across a membthat requires E b/c it is going against the normal movement of particlesProteins use E

2 types:endocytosis

phagocytosis (“cell eating”) pkg it w/in a food vacuole & engulf it

pinocytosis tiny pkgs filled w/ liquid

exocytosis

Molecule tobe carried

Moleculebeing carried

Energy

Section 7-3Active Transport

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?

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.

Adipocytes = fat cells

Muscle cell Smooth muscle tissue Stomach Digestive system

Section 7-4

Levels of OrganizationSo you see why the levels of biological organization work?

HOMEWORK!

Review your notes!

Finish any unfinished note-taking from last class.