The Cells and Eukaryotic Cells

Human Cell Size

10 - 15 Microns in Diameter

• Egg Cells → 100 Microns

• Nerve Cells → 1 Meter Long

  • Longest Human Cell

Basic Components of Cell

Plasma (Cell) Membrane

• Surrounds Cell

Cytoplasm

• Organelles

• Cytoskeleton

• Cytosol

  • Intracellular Fluid (ICF)

Extracellular Fluid

Cell Theory

Everything Comprised of 1+ Cells

Smallest Unit of Life

Arise from Preexisting Cells

Principle of Complementarity

• Biochem Activities dictated by Subcellular Structures

  • Organelles Determine Function

Specialization and Complexity

Due to Organization of Organs

• Made up of Individual Cells
  
  

Cells in Tissue Tasked Differently

Cells Tailor their Internal

Compartmentalization in Eukaryotic Cells → Task in Specific Places

Cell Membranes

Surrounds Organelles

Selective Permeability

Thin

Phospholipid Bilayer

Plasma Membrane

• Phospholipid Bilayer - 2 Sheetlike Layers

Phospholipid Makeup → Selectivity

• Head → Polar → Hydrophilic

• Tails → Nonpolar → Hydrophobic

Non Polar Pass Through

Polar No Pass

Fluid Mosaic Characteristics

Plasma Membrane is a “Fluid Mosaic”

• Proteins Floating In or On Phospholipid Bilayer

• Kinked Tails → Prevent Tight Packing

Mixed Composition

• Phospholipids → Primary Components

• Cholesterol → 20% of Membrane Lipids

• Glycolipids → 5% of Membrane Lipids

• Proteins → 2% of Molecules, 50% of Membrane Weight

• Glycoproteins

Action of Membrane Proteins

Six Types

• Transport

• Enzyme

• Receptor - Binding Site

• Recognition - Identification

• Intercellular Joining - Adhesion

• Attachment - To Cytoskeleton or Extracellular Matrix

Glycocalyx

Fuzzy Coat External to Plasma Membrane

• Carbohydrate part of membrane Glycoproteins and Glycolipids

• Identical in Twins

Functions

• Protection

• Immunity

• Cancer Defense

• Transplant Compatibility

• Adhesion

• Fertilization

• Egg Development

Microvilli

Extensions of Membrane

Increase Surface Area

Good for Absorption

“Brush Border”

Cytoskeleton

Cell Skeleton

Network of Protein Filaments and Tubules

Extend from Nucleus to Plasma Membrane

Maintain Shape

Lets Cells and Organelles Move

3 Cytoskeletal Components

Microfilaments → Change Cell Shape

Intermediate Filaments → Maintenance

Microtubules → Maintenance and Movement

Cilia and Flagella

Cell Motility

Flagella Longer and Fewer than Cilia

Movement or Moves Fluid

Cytoplasm

Cellular Material in Cell

3 Major Elements

• Cytosol → Viscous Liquid

• Organelles → Tiny Organs

• Inclusions → Chemicals

  • Not Always

  • Stored Nutrients + Lipids + Pigments

Organelles

Internal Organs → Carry Tasks

Nonmembranous Organelles

• Ribosomes, Centrosomes, Centrioles, Basal Bodies

Membranous Organelles

• Nucleus, Endoplasmic Reticulum, Golgi Complex, Lysosomes, Peroxisomes, Mitochondria

Centrioles

Short Microtubules in 9 Groups of 3

2 Centrioles in Cytoplasm called Centrosome

Cell Division

Ribosomes

Protein Factories

Large and Small Subunit

• Has different Mix of Protein and Ribosomal RNA

Free Floating in Cytosol or with Rough Endoplasmic Reticulum

Endomembrane System

Nucleus

Rough ER

Smooth ER

Golgi Body

Lysosomes

Various Vesicles

Nucleus

Largest Organelle

Control Center

Stores Genetic Info

Three Structures

• Nuclear Envelope → Membrane

• Nucleolus → Nucleoli

• Chromatin

Nuclear Envelope

Nucleus Bounded by Double Membrane Layer → Nuclear Envelope

Outer Membrane continuous with Rough ER

DNA NEVER LEAVES THE NUCLEUS

Nuclear Pores

Nucleus is Site of DNA Transcription and Synthesis

Nuclear Pores → Required for Material to Enter + Leave Nucleus

• Materials for Nucleotides

• Enzymes

• ATP

Surrounded by Protein Molecules → Gatekeepers

Nucleolus

“Little Nucleus”

Darker and Denser

Most have 1 or 2

Site of Ribosomal RNA Synthesis

Chromatin

DNA + Histone Proteins

DNA Chains wrapped around Proteins → Chromatin

Coiled to make Chromosomes

Nuclei in Cells

Most Cells have 1 Nucleus

Some Cells are Multinucleate

• Skeletal Muscle, Liver, Bone Destruction Cells
  
  

Mature Red Blood Cells are Anucleate

• No Nucleus

• Nucleus during Dev

• Can’t Reproduce

• Can’t Make Protein

Rough and Smooth Endoplasmic Reticulum

Smooth ER → Lacks Ribosomes

• No Protein Synthesis

• Site of Synthetic Processes

  • Lipid Metabolism

  • Cholesterol Synthesis

  • Steroid Hormone Synthesis

  • Fat Absorption, Synthesis, Transport

• Detoxification

• Storage

Rough ER → Has Ribosomes

• Makes Proteins

Golgi

3 - 20 Membranous Sacs

• Pancakes

Molecular UPS Store

• Receives Protein-Filled Vesicles from ER

• Modifies, Sorts, and Ships

• Rough ER and Golgi bounded by Single Layer of Membrane

  • Vesicles can Come and Go by Merge

Lysosomes

Intracellular Digestion

Buds Off from Golgi

Mix of Enzymes for Macromolecule Breakdown

Acidic Interior → pH 5

Autophagy → Digest and Dispose Old Organelles

Autolysis → Do Job and Die

Job

• Break Down Large Molecules

  • Old Organelles → Autophagy

  • Glycogen to Glucose

  • Whole Cells → Autolysis

    • Tadpole Tails

  • Bones to Calcium

Peroxisomes

Breakdown Fatty Acids and Amino Acids

Neutralize Free Radicals

Enzymes Produce Hydrogen Peroxide as Byproduct

• Toxic to Cells

• Catalase Breaks it Down

Mitochondria

Cellular Respiration

• ATP from Glucose and Oxygen

All Eukaryotic (Has Nucleus) Cells Contains at Least One

Inside

• Cristae → Folds in Inner Membrane

• Fluid called Matrix
  
  

Thought to Once Been Prokaryotic Bacteria

• Can Replicate Themselves

• Has Ribosomes and DNA Molecule

Eukaryotic Cells

Larger + More Complex than Prokaryotic Cells

Characterized by Internal Compartmentalization

Nucleus

Endomembrane System → Proteins and Lipids and Stuff

• Other Membrane Organelles are NOT part of Endomembrane System

  • Mitochondria, etc.

Cytoskeleton

Cytoplasm

Cell Membrane

Vacuoles

Membrane-Enclosed Space in Cytoplasm

• Storage

From Golgi Apparatus

In Plants, Has Surrounding Membrane → Tonoplast

Types of Vacuoles

Food Vacuoles → In Amoeba and Other Single Cell Organisms

Contractile Vacuoles → Regulate Water Content of Single Celled

Central Vacuole → In Plant Cells

• 95% Cell Volume

• Storage for Food, Toxins, Pigments, Ions

• Maintain Plant Cell Shape and Water Content

Energy Organelles

Mitochondria → Cellular Respiration

• ATP

Chloroplasts → Photosynthesis

• Light to Glucose

Chloroplasts

Photosynthesis Takes Place

Plans, Algae, and Cyanobacteria

Circular DNA Molecule + 70S Ribosomes like Prokaryotes

Double Membrane

Within Inner Membrane → Thylakoid Membrane

• Folded Network of Interconnecting Disks

  • Stacked to make Grana

• Fluid Inside → Stroma
  
  

Chlorophyll → Pigment within Thylakoid Membrane

• Captures Sunlight

Stroma → Enzymes for Catalysis

NO Chloroplasts in Cyanobacteria → Does have Thylakoid Membrane Though

Endosymbiosis Theory

Mitochondria WERE Bacteria

Chloroplasts WERE Cyanobacteria

Infected or Eaten by Other Species

End up Living Together

• Endosymbiosis