The Cell

1
The Cell

• Chapter 2

2
Outline

• Cell theory
• Eukaryotic cell
• Cell structure
• Cell function

3
Cytology

• Study of structure and function of cell
• Identified by Robert Hooke, 1665
• 50-100 trillion!!!

4
Cell Theory

• All known living things are made up of cells
• The cell is the structural and functional unit of
  all living things
• All cells come from pre-existing cells by
  division
• Cells contain hereditary information which is
  passed from cell to cell during cell division
• All energy flow (metabolism biochemistry) of
  life occurs within cells

5
Cell Categories

• Sex cells
• Cells specialized for sexual reproduction
• Found only in the gonads
• Created by meiosis
• Somatic cells
• All remaining cells in the body
• Varied in structure function
• Created by mitosis

Sex Cells
6
Somatic Cells
Cells exhibit patterns of form and function
7
The Cell in a Nutshell
8
Extracellular Matrix

• The substance in which animal tissue cells are
  embedded
• Matrix structure
• Proteins
• Polysaccharides
• Support
• Adhesion
• Movement
• Regulation

9
Membrane Structure Function

• Plasma membrane
• Phospholipid bilayer
• Fluid Mosaic model
• Selective permeability
• Function
• Physical isolation
• Regulation of exchange with the environment
• Sensory
• Structural support

10
Phospholipid Membrane
11
Fluid Mosaic Model
12
Membrane Proteins
13
Cell Recognition
14
Cytoskeleton

• Infrastructure of cell
• Maintains shape
• Mechanical support
• Organelle suspension
• Movement
• Cell division

15
Cytoskeleton Elements

• Microfilaments
• Connect with cell proteins
• Active movement
• Ex muscles
• Microtubules
• Cell skeleton
• Spindle fibers, cilia, flagella
• Microvilli
• Projections of cell surface
• Increase surface area
• Ex small intestine

16
Microfilaments

• http//dept.kent.edu/projects/cell/intro2.htm

17
Cilia Flagella
Microtubule (9-2)
18
Microvilli increase surface area
19
Cytoplasm

• Space inside the cell contains contents of the
  cell
• Cytosol
• Intracellular fluid
• Contains
• Dissolved nutrients ions
• Proteins enzymes
• Amino acids lipids
• Wastes nutrients
• Inclusions- stored nutrients
• Glycogen granules
• Lipid drops
• Organelles

20
Organelles

• little organs
• Specialized compartmentalized regions of cell
• Perform specific functions
• Vary according to cell function
• Suspended in cytosol, anchored by cytoskeleton

21
Nucleus

• Nuclear envelope
• Double membrane
• Nuclear pores
• Chromatin
• (Chromosomes)
• Nucleolus

22
Chromatin vs Chromosomes
23
Ribosomes

• Produced in the nucleus by nucleolus
• Active in cytoplasm
• Cytosol- free
• Endoplasmic reticulum- fixed
• Site of protein synthesis

24
Endomembrane System

• Multi-organelle system
• Functions in synthesis distribution of cellular
  products
• Endoplasmic reticulum
• Smooth rough
• Golgi apparatus
• Vacuoles

25
Endoplasmic Reticulum

• Tube sac structure
• Internal compartment
• Smooth ER
• Enzymes
• Lipid synthesis
• Detoxification
• Rough ER
• Ribosome
• Membrane proteins
• Secretory proteins

26
Golgi Apparatus

• Storage, modification, distribution
• Enzymes other proteins
• Receive products from ER
• Address packages

27
Vacuoles aka Vessicles

• Membranous sacs
• Functionally variable
• Derived from organelles
• ER
• Golgi
• Plasma membrane
• Diverse function
• Movement/ Pumps
• Transport vesicles
• Intracellular Digestion
• Lysosomes
• Storage
• Toxins
• Food

28
Lysosome

• Breakdown body
• Sacs of Digestive enzymes
• Proteins
• Polysaccharides
• Fats
• Nucleic acids
• Damaged cells organelles

29
Lysosomal Storage Diseases

• Disease of missing lysosomal enzyme
• Results in an inability to process molecules
  naturally
• Results in the accumulation of the undigested
  molecule until they interfere with cell function
• Ex. Tay-sachs disease
• Missing enzyme that breaks down lipids in nerve
  cells
• Impairs nerve function causes

30
Mitochondria

• Powerhouse of the cell
• Conversion of chemical energy to cellular energy
• Production of ATP via aerobic respiration

31
Cell Function

• Membrane Permeability
• Ability of molecules to move in /or out of a
  cell
• Selectively permeable
• Allows passage of some but not others
• Size
• Electrical charge
• Molecular shape
• Lipid solubility

32
Membrane Transport

• Passive transport
• No direct energy investment required
• Diffusion
• Osmosis
• Filtration
• Facilitated diffusion
• Active transport
• Requires ATP

33
Diffusion

• Net movement of molecules from an area of high
  concentration to and area of low concentration
• Driven by random movement
• High concentration to low concentration
• down a concentration gradient
• Dynamic equilibrium
• The tendency for molecules to spread out evenly
  in an available space
• Net movement

34
Diffusion can occur across a membrane
35
Osmosis

• Passive transport of a solute (water) across a
  selectively permeable membrane
• Pattern of net movement
• Movement directed by solute concentrations
  pressure

36
Osmoregulation
37
Filtration

• Movement of a fluid across a semi-permeable
  membrane
• Driven by pressure

38
Facilitated Diffusion

• Passive diffusion across a selectively permeable
  membrane with the assistance of a carrier
  membrane protein
• Requires NO ATP

39
Active Transport

• Requires cellular energy (ATP)
• Works against concentration gradient
• Endocytosis
• Phagocytosis
• Pinocytosis
• Exocytosis

40
Endocytosis Exocytosis
Possible because of the fluid nature of the
plasma membrane
41
Cell Division

• Duplication division separate stages
• Interphase
• Mitosis cytokinesis
• 2 types of division
• Mitosis
• Meiosis
• Differential rates