Biology

Ch. 7

Ms. Haut

Robert Hooke Used early compound

microscope to look at slices of cork

Named the tiny chambers “cells” after rooms in monasteries ht

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Anton van LeeuwenhoekDutch janitor with

hobby of ocular grinding (making lenses)

Used single-lens microscope to look at raindrops

Found living organisms

https://mattwells.wikispaces.com/Biology+K

Schleiden concluded plants were made of cells (1838)

Schwann concluded animals were made of cells (1839)

Virchow concluded new cells could only be produced from existing cells (1855)

Principles of Cell Theory:1. All living things are

composed of cells.2. Cells are the basic

units of structure and function in living things.

3. New cells are produced from existing cells.

The light microscope enables us to see the overall shape and structure of a cell

Figure 4.1A

Image seen by viewer

Eyepiece

Ocularlens

Objective lens

Specimen

Condenser lens

Light source

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Red blood cells

teaching.path.cam.ac.uk/partIB_pract/NHP1/

Invented in the 1950sThey use a beam of

electrons instead of light

The greater resolving power of electron microscopes • allows greater

magnification • reveals cellular details

websemserver.materials.ox.ac.uk/cybersem/getf...

Electron beam scans cell surfaceUsed to see detailed structure of cell surface

Figure 4.1B

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Red blood cellshttp://commons.wikimedia.org/wiki/Image:SEM_blood_cells.jpg

Transmits electrons through specimenUsed to examine the internal structures of a cell

Figure 4.1CCopyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Red blood cell in capillary

commons.wikimedia.org/wiki/Image:A_red_blood_...

Cell size is limited by metabolic requirementsLower limits:

Enough DNA to program metabolism

Enough ribosomes, enzymes, & cellular components

Upper limits:Surface area and

plasma membrane large enough for cell volume to allow exchange of nutrients and wastes

ProkaryotesSmaller cellsSimpler structureCells do not have a nucleusCells do not have membrane

bound organellesSingle celled organisms

EukaryotesLarger cellsMore complex structureCells have a nucleusCells have membrane bound

organellesSingle celled organisms—ProtistsMulticellular organisms

All Cells:1. Are surrounded by a cell membrane2. At some time during their life contain DNA

Single cellEnclosed by a plasma

membrane Usually encased in a

rigid cell wall • The cell wall may be

covered by a sticky capsule

Inside the cell are its DNA and other parts

Ribosomes

Figure 4.4

Capsule

Cell wall

Plasmamembrane

Prokaryoticflagella

Nucleoid region(DNA)

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All other life forms are made up of one or more eukaryotic cells

These are larger and more complex than prokaryotic cells

Eukaryotes are distinguished by the presence of a true nucleus

Structure:Nuclear envelope: double

membrane perforated with pores

Contains most of cell’s DNA in form of chromatin (DNA and protein)

Houses nucleolusMakes ribosomal parts

Function:Control center of cellDirects protein synthesis

Structure:RNA and proteins

found throughout cytoplasm and attached to endoplasmic reticulum

Function:Site of protein synthesis

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• Cells that are active in making proteins have lots of ribosomes

Structure:Channels made of

membranesSmooth ER

Synthesizes lipids, phospholipids, and steroids

Carbohydrate metabolismDetoxifies drugs & poisons

Rough ERProtein synthesisMembrane production

Have lots of Smooth ERExtract many harmful

materials from the blood and excrete them in the bile or from the kidneys.

http://www.zoology.ubc.ca/~berger/B200sample/unit_8_protein_processing/images_unit8/0_300_er.jpg

Structure:Stack of membranes

Function:Modify, sort and

package proteins and other molecules for storage in cells or secretion out of cells

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http://cellbiology.med.unsw.edu.au/units/images/tem_golgi1.jpg

Structure:Small membrane sack

filled with enzymesFunction:

Digestion of lipids, carbohydrates, and proteins

Break down worn out organelles

http://publications.nigms.nih.gov/insidethecell/ch1_animalcell_big.html

http://publications.nigms.nih.gov/insidethecell/images/ch1_lysosome.jpg

Structure:Small membrane

sack filled with enzymes

Function:Contain enzymes for

specific metabolic pathways; all contain hydrogen peroxide

Contain catalase 2H2O2 catalase 2H2O + O2

Structure:Saclike structures of

membraneFunction:

Store materials like water, salts, proteins, and carbohydrates

Stores food for digestion once lysosome fuses with it

Stores organic compounds

Stores inorganic ions

May contain pigments

May contain poisonsPlays role in plant

growth & elongation

Protists may have contractile vacuoles• These pump out

excess water

Figure 4.13B

Nucleus

Contractilevacuoles

Copyright © 2003 Pearson Education, Inc. publishing Benjamin CummingsCollapsing contractile vacuole of Protozoawww.microscopy-uk.org.uk/.../vidjuna.html

Structure:Enclosed by double

membraneContains ribosomes and

own DNA (maternal)Function:

Responsible for Cellular Respiration (converts chemical energy in glucose into chemical energy in ATP)

Grows and reproduces by itself

Structure:Enclosed by double

membraneContains ribosomes

and own DNA Function:

Site of photosynthesis in plants (converts solar energy into chemical energy in glucose)

http://www.s-cool.co.uk/assets/learn_its/alevel/biology/cells-and-organelles/organelles/chloroplast-b.gif

Structure:Network of protein

filamentsMicrofilaments-made of

actinMicrotubules-hollow

tubules made of tubulin

Function:Helps maintain cell

shape

MicrofilamentsTough, flexible framework

that supports cellCell movement-assembly

and disassembly for cytoplasmic movement

MicrotubulesForm mitotic spindle for

separating chromosomes

Form cilia and flagella for cell movement

Amoebahttp://plantphys.info/organismal/lechtml/images/amoeba.jpg