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Cell Structure and Function

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Presentation on theme: "Cell Structure and Function"— Presentation transcript:

1 Cell Structure and Function
1. The Cell Theory A. All organisms composed of one or more cells B. Cell is smallest living organizational unit C. Cells arise only from division of other cells

2 Attributes of cells A. Plasma membrane B. DNA C. Cytoplasm
D. Obtain energy and nutrients from their environment

3 Cell Size 1–100µ Cell Size A. Limitations of molecular diffusion
1. Faster passage through small cell 2. More efficient communication B. Limitations of surface-to-volume ratio 1. With increase in size, greater increase in volume than surface area a. Interaction with outside occurs only at surface b. Insufficient exchange of materials at plasma membrane for survival

4 diameter of DNA double helix
tallest trees adult human chicken egg frog embryo most eukaryotic cells mitochondrion Figure: 04-01 Title: Relative sizes. Caption: Dimensions commonly encountered in biology range from about 100 meters (the height of the tallest redwoods) through a few micrometers (the diameter of most cells) to a few nanometers (the diameter of many large molecules). most bacteria virus proteins diameter of DNA double helix atoms

5 Cell types Prokaryotic—no nucleus, circular DNA, ribosomes, peptiglycon-prokayotic cell wall a. Carbohydrate matrix cross linked with peptide units Eukaryotic—larger, nucleus, linear chromosomes, membraned organelles, Compartmentalization Include true bacteria On earth 3.8 million years Found nearly everywhere Spores in each breath; intestines Naturally in soil, air, hot springs

6 nucleoid (DNA) ribosomes food granule cytoplasm cell wall
prokaryotic flagellum Figure: 04-10 Title: A generalized prokaryotic cell. Caption: plasma membrane cytoplasm cell wall

7 Eukaryotic Cells Have numerous internal structures
Various types & forms Plants, animals, fungi, protists Multicellular organisms Nucleus is control center of the cell 1. Membrane bound (nuclear envelope) 2. Contains nucleoli; synthesizes ribosomal RNA 3. DNA in chromosomes (DNA and proteins)

8 1. Plant cells a. Square-geometric shaped b. Cell wall- cellulose
c. Chloroplast d. No centrioles e. Large vacuoles

9 (part of cytoskeleton)
microtubules (part of cytoskeleton) mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle cell wall rough endoplasmic reticulum plasma membrane Figure: 04-03 Title: A generalized plant cell. Caption: nucleolus nuclear pore nucleus chromatin nuclear envelope intermediate filaments ribosomes free ribosome

10 Animal Cells a. Irregular shaped b. Just Cell membrane c. Small vacuoles d. Centrioles

11 nuclear pore chromatin (DNA) nucleus nucleolus nuclear envelope
flagellum intermediate filaments cytoplasm plasma membrane rough endoplasmic reticulum ribosome lysosome microtubules Figure: 04-02 Title: A generalized animal cell. Caption: smooth endoplasmic reticulum Golgi complex free ribosome vesicle mitochondrion vesicle

12 nuclear envelope nucleolus nuclear pores chromatin Figure: 04-04a
Title: The nucleus. Caption: (a) The nucleus is bounded by a nuclear envelope. Inside are chromatin (DNA and associated proteins) and a nucleolus. chromatin

13 nucleus nuclear pores Figure: 04-04b Title: The nucleus. Caption:
(b) An electron micrograph of a yeast cell that was frozen and broken open to reveal its internal structures. The large nucleus, with nuclear pores penetrating its nuclear envelope, is clearly visible.

14 chromatin chromosome Figure: 04-05 Title: Chromosomes. Caption:
Chromosomes, seen here in a light micrograph of a dividing cell (on the right) in an onion root tip, are the same material (DNA and proteins) as the chromatin seen in nondividing cells adjacent to it, but in a more compact state. chromosome

15 Figure: 04-06 Title: Ribosomes. Caption: 0.05 micrometers

16 Eukaryotic cell structure
Organelles Endoplasmic reticulum consists of folded membranes attached to the nucleus Rough ER is site of protein synthesis and protein secretion. Proteins made here are processed and shipped out of the cell

17 Eukaryotic Cell Structure
Ribosomes assemble amino acid into polypeptide chains a. Associated with the ER b. Composed of RNA and proteins Proteins for inside the cell

18 rough endoplasmic reticulum
ribosomes Figure: 04-07R-1 Title: Rough endoplasmic reticulum. Caption: rough endoplasmic reticulum 0.5 micrometers

19 smooth endoplasmic reticulum
vesicles Figure: 04-07R-2 Title: Smooth endoplasmic reticulum. Caption: smooth endoplasmic reticulum 0.5 micrometers

20 Eukaryotic Cell Structure
Golgi apparatus are membranous sacs associated with ER Processing and transport of proteins, lipids exported from the cell Synthesis and transport of polysaccharides Lysosomes are Golgi-derived vesicles containing digestive enzymes

21 ____________________________________________________________________________________________________________________________________________________________________________________________________

22 vesicles from ER vesicles leaving Golgi complex Golgi complex
Figure: 04-08 Title: The Golgi complex. Caption: The Golgi complex is a stack of flat membranous sacs. Vesicles transport material from the ER to the Golgi (and vice versa) and from the Golgi to plasma membrane, lysosomes, and vesicles. Departing vesicles bud off from the Golgi on one face; arriving vesicles join it on the opposite face.

23 Energy sources for cell activities
Mitochondria provide energy for cellular functions (respiration) a. Matrix/cristae b. Have their own DNA and ribosomes; self- replicate C. Bounded by double membrane-numerous a. Outer membrane is smooth b. Inner membrane is folded into contiguous layers called cristae 1. Cristae are stuffed with 100,000 enzymes 2. Site of cellular respiration-Oxidation 3. Divides into inner matrix and outer compartment 4. Associated with proteins of oxidative metabolism


25 5 micrometers Figure: 04-E4-2d Title: An SEM photo. Caption:
(d) An SEM photo at much higher magnification, showing mitochondria, many of which are sliced open. 5 micrometers

26 Energy sources for cell activities
Chloroplasts—function in photosynthesis 1) Green—contain chlorophyll pigment 2) Stroma/grana (thylakoid stacks) 3) Have their own DNA and ribosomes; self-replicate 4) Up to 100 per cell 5) Become leucoplasts when deprived of light a. Specialized amyloplasts store starch b. Plastids are derived from proplastids



29 Cytoskeleton Cytoskeleton Surface structures Internal infrastructure
a. Actin filaments-microfiliments a. Muscle movement b. Pinches cell when it divides during cytokinesis b. Microtubules 1. Hollow tubes of 13 protein protofilaments-made of tubulin 2. Function a. Help move materials within the cell itself b. Skeletal System c. Aides in cell Division-spindle d. Cilia, Flagella, sperm tails c. Intermediate filaments Surface structures extensions of the plasma membrane aid in movement of simple organisms

30 actin subunits subunit tubulin subunit Figure: 04-2 Title:
Cytoskeleton components. Caption: tubulin subunit



33 Prokaryotes & Eukaryotes
Similarities & differences Both surrounded by plasma membrane, but very different Prokaryotes – Archaebacteria and Eubacteria Eukaryotes – everything else

34 ____________________________________________________________________________________________________________________________________________________________________________________________________

35 Evolution of Eukaryotic cell
Endosymbiotic Hypothesis Similarities between bacteria, mitochondria and chloroplasts Self-reproducing by binary fission Size of organism and genome Single circular naked DNA Proportion of (G & C) to (A & T) Same sized ribosome Protein synthesis inhibited by antibiotics Enzymes for synthesis of DNA, RNA and protein Electron transport system

36 ____________________________________________________________________________________________________________________________________________________________________________________________________


38 Plant & Animal Cells Similarities
Both constructed from eukaryotic cells ________________________________________________________________________________ Both contain similar organelles __________________________________________________________________________________ Both surrounded by cell membrane _________________________________________________________________________________

39 Plant & Animal Cells Differences Animals have Plants have
Cell wall – provides strength & rigidity Have chloroplasts, photosynthetic Animals have Other organelle not found in plants (lysosomes formed from Golgi) Centrioles, important in cell division

40 Brief Look at Viruses Viruses are acellular
Not considered to be living Cause serious diseases in most organisms


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