Cell Structure

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

CELL STRUCTURE

Chapter 3

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Introduction

• The cell is the basic unit of biological organization

• Basic composition– Protoplasm– Cell membrane– Organelles

• Eukaryotic vs. prokaryotic


HISTORY OF THE CELL THEORY


History of the Cell Theory

• Proposed in 1830s by Schleiden and Schwann

• Modern cell theory– Cells are smallest complete living things– All organisms are composed of one or more

cells


History of the Cell Theory (cont’d.)

• Modern cell theory– Cells arise only from other cells– All existing cells are descendants of the first

cells


ANATOMY OF A TYPICAL EUKARYOTIC CELL


Introduction


The Cell Membrane

• Double phospholipid layer with embedded proteins


The Cell Membrane (cont’d.)

• Membrane transport: selectively permeable membrane– Osmosis– Protein channels– Active transport– Fluid mosaic model


Cytoplasm of the Cell

• Mostly water with chemical compounds in solution or colloid– Solution vs. colloid

• Individual vs. clumped atoms or ions distributed in medium


Cytoplasm of the Cell (cont’d.)

• Polar compounds go into solution

• Nonpolar compounds go into colloidal suspension


The Nucleus

• Control center of the cell

• Nuclear membrane has pores to allow substances passage

• Chromatin genetic material inside nucleoplasm

• Nucleolus: site of ribosome formation


The Mitochondria

• Powerhouses of the cell

• Cristae: inner folds where cellular respiration occurs

• Energy requirements of cell determine cristae number


Lysosomes

• Digestive enzyme packages

• Function– Digest stored food– Maintenance and repair of organelles– Suicide agents for old or weak cells


Endoplasmic Reticulum

• System of membranes that makes up channels

• Connects with outer nuclear and cell membranes

• Cisternae: sac-like or channel-like cavities


Endoplasmic Reticulum (cont’d.)

• Rough ER– For protein synthesis– Attached ribosomes

• Smooth ER– Fat transport– Sex hormone synthesis


Endoplasmic Reticulum (cont’d.)

• Golgi apparatus– Collection of flat saclike cisternae– Concentration and collection of cellular

compounds– Storage warehouses of the cell– Carbohydrate synthesis site


Ribosomes

• Distributed throughout cytoplasm

• Attached to rough endoplasmic reticulum

• No membrane covering

• Site of protein synthesis


Ribosomes (cont’d.)

• Protein functions– Structure, enzymes or catalysts, immune

response

• DNA contains the code for a particular protein– DNA found in nucleus



• Transcription– Messenger RNA copies DNA code and leaves

nucleus

• Translation– Transfer RNA picks up amino acids– Ribosomes link amino acids together


Centrioles

• Centrosome: two centrioles at right angles to each other– Composed of nine sets of triplet fibers

• Form spindle fibers during cell division

• Guide duplicated chromosomes to daughter cells


Cilia and Flagella

• Hairlike protrusions from cell membrane

• Nine double fibrils around two single central fibrils

• Cilia move materials across cell surface

• Flagellum propels cell through a medium


Animation – Anatomy of a Typical Cell

Click Here to Play Anatomy of a Typical Cell Animation


Plastids of Plant Cells

• Chloroplasts– Most common plastid– Photosynthesis: conversion of light into

chemical energy– Granum

• Made of thylakoids• Connected by lamella


Plastids of Plant Cells (cont’d.)

• Chromoplasts: carotenoid pigments

• Leucoplasts: store food

• Cell membrane surrounded by cell wall


Plastids of Plant Cells (cont’d.)

• Cell wall composed of cellulose– Cellulose

• Dietary fiber• Synthesized by Golgi bodies

• Animal cells do not have cell walls


Summary

• Discussed the modern cell theory and its origins

• Discussed the different parts of eukaryotic cells including the cell membrane, cytoplasm and organelles


Summary (cont’d.)

• Discussed protein synthesis

• Described some of the differences between plant and animal cells

Cell Structure

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