Bi 121 Chapter 3 Lecture Power Point

Front 1

Cellular activity

Back 1

• Foundation for bodily functions
  
• Dysfunction, source of disease
• Foundation for rest of study of anatomy and physiology

Front 2

Cytology

Back 2

Study of cellular structure and function

• 200 kinds of cells in human body
  

Front 3

Components of a cell

Back 3

• Plasma membrane (cell membrane)
• Cytoplasm
• Cytoskeleton
• Organelles
• Inclusions
• Cytosol

Front 4

Plasma membrane (cell membrane)

Back 4

Forms a cell's surface boundary

Front 5

Define Cytoplasm

Back 5

Material between plasma membrane and nucleus

• nucleus largest organelle

Front 6

Parts of cytoplasm

Back 6

• Cytoskeleton: supportive framework of filaments and tubules
• Organelles: diverse structures performing tasks for the cell
• Inclusions: accumulated cell products. (lipids, pigments, and bacteria.)
• Cytosol: clear gel embedding the other components.

Front 7

Cytosol

Back 7

Clear gel embedding the other components

Front 8

ICF

Back 8

Intracellular fluid

Front 9

ECF

Back 9

Extracellular fluid

• refers to all body fluids on ICF
• ECF between cells termed tissue fluid
• also blood plasma, lymph, and cerebrospinal fluid.

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micrometer

Back 10

10-6 meter

Front 11

size of most cells

Back 11

10-15 micrometers

Front 12

Why is cell size limited?

Back 12

• If too large it would rupture
• Diffusion efficiency
• Lessens impact of single cell death on organism

Front 13

Activities of cell surface

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• Binding of single molecules
• Stimulation of cellular activity
• Attachment of cells to each other
• Transport of materials into and out of cells

Front 14

Plasma membrane

Back 14

• Membrane at cell surface
• Defines boundary of cell
• Governs interactions with other cells
• Maintains chemical composition differences between ECF and ICF
• Two layered lipid film with embedded proteins

Front 15

What lipids are in plasma membrane?

Back 15

• Phospholipids
  
• Cholesterol
• Glycolipids

Front 16

Phospholipids

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• Highly fluid
• 75% of lipid molecules
• hydrophilic phosphate head

(faces water on inside and outside of cell)

• Two hydrophobic fatty acid tails

(forms middle of phospholipid bilayer away from water)

Front 17

Cholesterol

Back 17

• 20% of lipid molecules
• Affects membrane fluidity
• If too much, inhibits protein and enzymes in membrane
• If too little, plasma membrane too fragile

Front 18

Gycolipids

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• Remaining 5% of lipid molecules
• Phospholipids with short extracellular carbohydrate chains

Front 19

Types of membrane proteins

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• Integral proteins
• Peripheral proteins

Front 20

Integral proteins

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• Proteins that penetrate cell membrane
• most glycoproteins (proteins with carbohydrates attached.)

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Peripheral proteins

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• Do not protrude into phospholipids
• usually on intracellular face

Front 22

Function of membrane proteins

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• Receptors
• Enzymes
• Channel
• Carriers
• Cell-identity markers
• Cell-adhesion molecule (CAMs)

Front 23

Receptors

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• Membrane protein
• Receives and binds chemical signals from other cells

Front 24

Membrane Enzyme function

Back 24

• Carry out chemical reactions at membrane surface
• I.E. degrading signal molecules
• I.E. breaking down dietary nutrients

Front 25

Channel proteins

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• Have tunnels through them
• Allow water and hydrophilic solutes to enter or leave cell
• some always open
• other open and close at different times. (gated channel)

Front 26

Carrier (membrane protein)

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• Bind substance on one side of membrane
• release it on the other side
• transport glucose, amino acids, ions, and other substances

Front 27

Cell-identity markers

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• glycoproteins and glycolipids, cell identification tags
• unique to an individual
• enable immune system to distinguish body from anything foreign

Front 28

Cell-adhesion molecules (CAMs)

Back 28

• link cells to each other
• link cells to extracellular material
• bind tissue together
• also needed for sperm-egg binding
• needed for immune cell binding

Front 29

Types of Plasma membrane proteins

Back 29

Front 30

Characteristics of Glycocalyx

Back 30

• Fuzzy carbohydrate coat covering cells
• Short sugar chains of glycolipids and glycoproteins

Front 31

Functions of Glycocalyx

Back 31

• Cell-adhesion molecule
• Cushions and protects plasma membrane
• functions in ability to distinguish healthy cells from diseased cells, foreign organisms, and transplanted tissues.
• Determine human blood types and transfusion compatibility

Front 32

Microvilli

Back 32

• Extension of plasma membrane
• Serve primarily to increase surface area
• Better developed in cells specialized for absorption (small intestine)
• Well developed in taste buds and inner ear

Front 33

Visual of Microvilli and Glycocalyx (brush border)

Back 33

Front 34

Cilia

Back 34

• Hairlike extensions
  
• Most cells with solitary, nonmotile cilium may serve sensory function
• Modified cilia in many roles

light absorbing parts of retinal cells in eye

motion and balance in inner ear

monitoring fluid flow in kidneys

sensory cells of nose

Front 35

Motile cilia

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• Less widespread
• Abundant in mucous membranes of respiratory tract (to move mucus from lungs up to the throat)
• Abundant in uterine tubes (move egg or embryo toward uterus)

Front 36

Flagella

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• Resembles long solitary cilium
• Has same structure as cilia
• Stiffened by sheath of microfilaments
• In tail of sperm (used to crawl up mucous membrane of uterus)

Front 37

Cell junction function and characteristics

Back 37

• Formed by proteins at cell surface
• Link cells togeather
• Attach them to extracellular material
• Enable cells to grow and divide normally, resist stress, and communicate with each other.

Front 38

Types of Cell junction

Back 38

• Tight junctions
• Desmosomes
• Gap junctions

Front 39

Tight junction

Back 39

• Completely encircles epithelial cell near upper end. (joins tightly to adjacent cells)
• Formed by fusion of plasma membrane of adjacent cells
• Makes it difficult for substances to leak between cells (prevent digestive juices seeping between epithelial cells.)

Front 40

Desmosome

Back 40

• Holds cells together at specific point
• not continuous
• Keep cells from pulling apart
• Enable tissues to resist mechanical stress
• Common in epidermis and cardiac muscle

Front 41

Gap Junction

Back 41

• Formed by ring of proteins surrounding channel
  
• Aids diffusion through channel from cytoplasm of one cell into another. (ions, glucose, amino acids, other solutes.)
• I.E. in cardiac muscle allows electrical excitation to pass directly from cell to cell.

Front 42

Cell Junctions (picture)

Back 42

Front 43

Types of cell membrane transport

Back 43

• Selective permeability
  
• Simple diffusion

Front 44

Selective permeability

Back 44

• Allows some substances to pass
• Holds back others

Front 45

Simple diffusion

Back 45

• Net movement of particles from high concentration to low (down a concentration gradient)
  
• How oxygen and steroid hormones enter cell
• Does not require cell energy
• Random motion due to heat of molecules provides energy for simple diffusion from.

Front 46

How do nonpolar and hydrophobic substances pass the plasma membrane?

Back 46

Diffuse through lipid regions of membrane

Front 47

How do Hydrophilic substances pass the plasma membrane?

Back 47

Diffuse through protein channels of membrane

Front 48

Osmosis

Back 48

• Net movement of water from lower solute concentration to higher
• Water molecules loosely associated with solutes

makes less able to break free

water molecules on low solute side more able to pass through membrane

• Plays key role in homeostasis (cell volume and capillaries absorbing fluid)

Front 49

Facilitated diffusion

Back 49

• Carrier mediated transport (employ carrier proteins in plasma membrane)
• Movement of solute down concentration gradient
• Occurs with aid of carrier (binds particle on side where solute more concentrated and released on lower concentration side.
• No energy required by cell
• Transports solutes that can't pass membrane. I.E. sugar absorbtion.

Front 50

Active transport

Back 50

• Carrier-mediated transport
• Requires energy input (like rolling a wagon uphill)
• Moves solutes up its concentration gradient (from less concentrated to more)
• Ceases immediately without ATP energy.

Front 51

Sodium-potassium (Na-K) pump

Back 51

• Important active-transport process (uses ATP and largest source of daily caloric needs)
• Sodium normally more concentrated in ECF
• Potassium normally more concentrated in ICF
• Binds three Na and pumps out of cell
• Binds two K and pumps into cell

Front 52

Sodium pump roles

Back 52

• Controlling cell volume
• Generate body heat
• Providing energy for other transport pumps

Front 53

Vesicular transport (define and types)

Back 53

• Move substances through membrane in vesicles (requires ATP)
• Endocytosis
• Exocytosis

Front 54

Endocytosis

Back 54

Movement of substances through membrane in vesicles INTO the cell (requires ATP)

Front 55

Exocytosis

Back 55

Movement of substances through membrane in vesicles OUT of the cell(requires ATP)

Front 56

Types of Endocytosis

Back 56

• Phagocytosis
• Pinocytosis
• Receptor-mediated endocytosis

Front 57

Phagocytosis

Back 57

• Cell eating
  
• footlike pseudopods reaching out from cell
• surrounds particle
• engulf and enzymatically degrade particle
• especially in macrophages (white blood cells)

Front 58

Pinocytosis

Back 58

• Cell drinking
• Occurs in all human cells
• formation of dimples in plasma membrane
• cave in and pinch off as vesicles
• contain droplets of ECF

Front 59

Receptor-mediated endocytosis

Back 59

• more selected membrane transport
• cell able to take in specific molecules from ECF
• specific receptor proteins on plasma membrane

1. cluster together
2. membrane sinks in here
3. pit pinches off, forming vesicle

I.E. insulin absorption from blood

Front 60

Exocytosis

Back 60

• Reverse endocytosis
• Secretory vesicle in cell

1. migrates to surface
2. fuses with plasma membrane
3. releases products from cell
4. becomes part of plasma membrane

I.E. digestive glands to secrete enzymes and breast cells to secrete milk

Front 61

Cytoskeleton

Back 61

• Network of protein filaments and tubules in cytoplasm
• Structurally supports cell
• Determines shape and organizes content
• Transports substances within cell
• Contributes to cell movements
• Connected to proteins in plasma membrane

Front 62

Microfilaments

Back 62

• Thinnest components to cytoskeleton
• Made of protein, actin
• Form dense fibrous mesh on internal plasma membrane (terminal web)
• 6 nm thick

Front 63

Intermediate filaments

Back 63

• Stiff intermediate components of cytoskeleton
• Contribute to strength of desmosomes
• Include tough protein keratin
• fills cells of epidermis and gives strength to the skin
• 8-10 nm diameter

Front 64

Microtubules

Back 64

• Thickest components of cytoskeleton
• Hold organelles in place
• Form bundles that maintain cell shape
• Like "monorails"
• Form axonemes of cilia and flagells
• Form centrioles and mitotic spindle
• 25 nm diameter

Front 65

Kinds of inclusions

Back 65

• Stored cellular products

I.E. pigments, fat globules, and glycogen granules

• Foreign bodies

Viruses, bacteria, and dust particles

• Never enclosed in a membrane
• Not essential to cell survival

Front 66

Organelles

Back 66

• Play individual roles to survival of cell
• Compartmentalized components of the cell

Front 67

Nucleus

Back 67

• Largest organelle
• Most cells with only one nucleus

Mature red blood cells don't have a nucleus

Skeletal and liver cells have multiple nuclei

Front 68

Nuclear envelope

Back 68

• Two parallel membranes surrounding nucleus
• perforated by nuclear pores

regular traffic into and out of nucleus

bind two membranes togeather

Front 69

Chromosomes

Back 69

• Threadlike bodies of DNA and protein
• Found in nucleus
• Most human cells with 46 chromosomes
• Chromatin, (form in nondividing cells) fine filaments dispersed throughout the nucleus.

Front 70

Chromatin

Back 70

Form of chromosomes in non dividing cells

• fine filaments dispersed throughout nucleus

Front 71

Nucleoli

Back 71

• One or more dense masses in nucleus
• Where subunits of ribosomes are made

Front 72

Endoplasmic reticulum

Back 72

• System of interconnected channels called cisternae

enclosed by a membrane

• Synthesizes steroid and other lipids
• Detoxifies drugs
• Manufactures cell's membranes
• Produces phospholipids and plasma membrane proteins
• Produces proteins for secretion of lysosomes

Front 73

Smooth endoplasmic reticulum

Back 73

• cisternae lack ribosomes
• continuous with rough ER
• abundant in cells that synthesize steroid hormones

I.E. the testes, ovaries

• abundant in cells specializing in detoxification

I.E. liver cells

Front 74

Rough endoplasmic reticulum

Back 74

• cisternae covered with ribosomes
• continuous with outer membrane of nuclear envelope
• most abundant in cells making lots of protein

Front 75

Ribosomes

Back 75

• Small granules of protein and ribosomal ribonucleic acid (rRNA)
• Produced in nucleus
• "Read" genetic messages from the nucleus
• Assemble amino acids into proteins specified by code
• Many attached to nuclear envelope and rough ER
• Others free in cytoplasm

Front 76

Golgi Complex

Back 76

• Small cluster of cisternae (flattened curved sac)
• Synthesize carbohydrates
• Complete protein and glycoprotein synthesis
• Pinch off membranous sacs, Golgi vesicles
• Some becoming lysosomes
• Some becoming part of plasma membrane
• Others becoming secretory vesicles (stored for later release by exocytosis)

Front 77

Golgi vesicles

Back 77

Membranous sacs filled with complex secretory products produced from golgi complex

Front 78

Lysosomes

Back 78

• Packages of enzymes enclosed in a membrane
• Often round or oval
• Break down (proteins, nucleic acids, and carbohydrates, phospholipids, and others.)
• Digest and destroy microbes in white blood cells
• Digest worn-out organelles
• Help carry out apoptosis

Front 79

Apoptosis

Back 79

Prearranged "cell suicide" in no longer needed cells

Front 80

Peroxisomes

Back 80

• Resemble lysosomes but contain different enzymes
  
• Abundant in liver and kidney cells
• Bread down fatty acids in two carbon molecules (can be used as energy or ATP synthesis)
• Neutralize free radicals
• Detoxify drugs
• Kill bacteria
• Produce hydrogen peroxide

Front 81

Mitochondria

Back 81

• Specialized for ATP synthesis
  
• Surrounded by double membrane

1. inner membrane with folds (cristae)
2. Space between cristae (mitochondrial matrix)

• Contains enzymes, ribosomes, and small DNA molecules call mitochondrial DNA. mDNA

Front 82

Mitochondria history

Back 82

• Were once free-living bacteria
• Internalized by another primitive cell
• Evolved to become permanent indispensable residents
• Mitochondrial DNA

circular loop like modern bacteria

genetically different from DNA in cell nucleus

mutations responsible for some muscle, heart, and eye disease.

Front 83

Centrioles

Back 83

• Short cylindrical assembly of microtubules
  

arranged in nine groups of three each

• Basal bodies of cilia and flagella considered solitary centrioles

Front 84

Centrosome

Back 84

• Patch of cytoplasm near nucleus
• contains pair of centrioles
• plays a role in cell division

Front 85

Visual of Centriole

Back 85

Front 86

Steps of protein synthesis

Back 86

1. DNA in nucleus with protein codes (genes)
2. Transcription: Copy made of gene (messenger RNA, mRNA) and mRNA migrates to cytoplasm
3. 
   
4. Translation: Reading of code by ribosomes (amino acids assembled in correct order)

Front 87

Transcription

Back 87

• First step of protein synthesis
  
• Begins at site of particular gene
• Double helix "unzipped"
• RNA polymerase (enzyme) reads bases and creates parallel molecule of messenger RNA. Mirror image of gene.
• mRNA "edited" in nucleus removing noncoding segments and to make mature mRNA molecule
• Exported through nuclear pore into cytoplasm

Front 88

DNA-------->mRNA transcription coding

Back 88

DNA mRNA

A ----------->U

T ----------->A

C----------->G

G----------->C

DNA: A(lways) T(ake) C(are) ATC

around

mRNA: U(nusually) A(gressive) G(eese) UAG

Front 89

Translation

Back 89

• mRNA translated into amino acids
• Small and large ribosomal subunits assemble on mRNA and begin reading coded message of mRNA

Front 90

Codons

Back 90

Three-base segments of mRNA

• 64 codons in genetic code
• 20 amino acids composing proteins
• some redundancy present
• each codon standing for particular amino acid

I.E. GGU,GGA,GGG glycine, AUG methonine, UAG, UGA, UAA

Front 91

Transfer RNA (tRNA)

Back 91

• Small RNA molecule
• Bound by ribosome as it reads codon
• Carries an amino acid
• Has complementary base series to codon (anticodon)
• Binds tRNA with anticodon CCA carries glycine added to protein by ribosome
• Repeats process as ribosome reads next codon

amino acids added one by one

continues until reaches stop codon

Front 92

Protein processing and secretion (Nucleus/ribosome/Rough ER)

Back 92

1. mRNA "docks" on rough ER
   
2. Protein reels into ER cisterna during assembly
3. Certain amino acid segments cut and spliced
4. Altered proteins shuffled into transport vesicles and carry protein to nearest cisterna of golgi complex.

Front 93

Protein processing and secreation (Golgi process)

Back 93

1. Sorts proteins
2. Passes from the one cisterna to the next
3. Further alters proteins (may add carbohydrates or other components)
4. budding off of gogli vesicles (become lysosomes or released by exocytosis)

Front 94

Picture of protein synthesis and secretion

Back 94

Front 95

Phases of cell division

Back 95

1. Gap 1, G1
   
2. Synthesis phase, S
3. Gap 2, G2
4. Meitotic phase, M

Front 96

First Gap phase G1 (cell division)

Back 96

• Interval between cell division and DNA replication
• Time of protein synthesis and growth
• Completion of normal cell tasks
• Begin replicating centrioles
• Accumulation of materials needed for DNA replication

Front 97

Synthesis phase (cell division)

Back 97

• Cell carrying out DNA replication (creates two sets of identical DNA molecules)
• DNA molecules "unzip" and separate into two strands
• DNA polymerase (enzyme) reads base sequence of DNA strands and assembles nucleotides to make complementary strand.
• Two enzymes work in opposite directions

Front 98

Picture of DNA replication

Back 98

Front 99

Second Gap G2 (cell division)

Back 99

• Relatively brief
• Interval between DNA replication and cell division
• Finishes replication of centrioles
• Synthesis of enzymes that control cell division

Front 100

Interphase

Back 100

• The time between cell division
  
• Consists of G1, S, and G2 phases of cell division.
  

Front 101

Phases of Mitotic phase

Back 101

• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

Front 102

Mitotic phase (M) (cell division)

Back 102

• period of mitosis
• Nucleus replicated
• DNA divided into two identical sets
• Cell pinching in half and creates two identical daughter cells

Front 103

Some examples of cell division time of cells

Back 103

• Fibroblasts (connective tissue cells) once a day
• Bone cells: divide slowly
• Skeletal nerve cells: no dividing at all
• Cancer: continually cycling

Front 104

Mitosis

Back 104

• Process of cell division in cells (except eggs and sperm which is meiosis)
  
• Develops fertilized egg into an individual
• Continue growth of organs after birth
• Repairs damaged tissues

Front 105

Prophase

Back 105

• Chromosomes coil into short dense rods
  
• Chromosomes have two identical bodies (sister chromatids) joined at center pinched spot (centromere)
• 46 chromosomes (two chromatics per chromosome (92 DNA molecules in all)
• Nuclear envelope disintegrates
• Spindle fibers (elongated microtubules sproute from centrioles pushing them apart)
• Centrioles attach to centromeres of chromosomes

Front 106

picture of a centromere/sister chromatid

Back 106

Front 107

Metaphase

Back 107

• Chromosomes aligned on cell equator
  
• Await signal to split in two at centromere

Front 108

Mitotic spindle

Back 108

• Array of spindle fibers
• Some reaching from centrioles to chromosomes
• Some anchoring assembly to inside of plasma membrane

Front 109

Anaphase

Back 109

• Centromere cleaved in two by enzyme and forms into sister chromatics NOT chromatids (called daughter chromosomes)
• Each daughter is genetically identical
• One daughter chromosome moved to each pole of cell by centromere
• Almost all body cells genetically identical except egg and sperm cells

Front 110

Telophase

Back 110

• Clustering of chromatics on each side of cell
• New nuclear envelop developes around each cluster made of rough ER
• Chromatids beginning to uncoil returning to dispersed form
• Mitotic spindle breaks up
• Nuclear division ends

Front 111

Cytokinesis

Back 111

• Division of cytoplasm
• Overlaps with telophase
• Motor proteins pulling on membrane skeleton
• Creates crease, cleave furrow around equator
• Cell pinches in two
• Transitions into interphase