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Flashcards in Chapter 3 Deck (82)
1

Cell

-Structural and functional unit of life
-Basic unit of life
-Organismal functions depend on individual and collective cell functions
-Biochemical activities

2

Cell Diversity

-Over 200 different types of human cells
-Types differ in size, shape, sub-cellular components, and functions

3

General Cell (All Cells)

-All cell have some common structures and functions
-Human cells have three basic parts:
--Plasma membrane
--Cytoplasm
--Nucleus

4

Plasma Membrane

Flexible outer boundary
-lipid bilayer and proteins constantly changing fluid mosaic
-plays dynamic role in cellular activity
Separates intracellular fluid (ICF) from extracellular (ECF)
--Interstitial fluid (IF)= ECF that surrounds cells

5

Membrane Lipids
Lipid Bilayer

Phospholipids
-Phosphate heads: polar and hydrophillic (water liking)
-Fatty acid tails: nonpolar and hydrophobic (water fearing)

6

Membrane Proteins

-Allow communication with environment
-Most specialized membrane functions
2 Types
-Integral Proteins
-Peripheral Proteins

7

Integral Proteins

Firmly inserted into membrane
-Have both hydrophobic and hydrophilic
-Function as transport proteins (channels and carriers), enzymes, or receptors

8

Peripheral Proteins

-Loosely attached to integral proteins
-Include filaments on intracellular surface for membrane support
-Function as enzymes

9

6 Functions of Membrane Proteins
(Look at Diagram Cards)

-Transport
-Receptors for signal transduction
-Attachment to cytoskeleton and extracellular matrix
-Enzymatic Activity
-Intercellular Joining
-Cell-cell recognition

10

Glycocalyx

"sugar coverings" at cell surface
-lipids and proteins with attached carbohydrates (sugar groups)
-Every cell has different pattern of sugars

11

Cell Junctions
2 types
3 subtypes

Some are "free"
EX- blood cells, sperm cells
Some bond into communities
3 types:
-Tight junctions
-Desmosomes
-Gap junctions

12

Tight Junctions

Adjacent integral proteins fuse form impermeable junction encircling cell
-prevents movement

13

Desmosomes

"Rivets" or "spot-welds" that anchor cells together at plaques (thickenings on plasma membrane)
-Linker proteins between cells connect plaques
-Lends stability to cell
-Reduces possibility of tearing

14

Gap Junctions

Transmembrane proteins form pores that allow small molecules to pass from cell to cell
-for spread of ions, simple sugars, and other small molecules between cardiac or smooth muscle cells

15

Plasma Membrane

Cells currounded by interstitial fluid (IF)
-contains thousands of substances; amino acids, sugars, fatty acids, vitamins, hormones, salts, waste products
Plasma membrane allows cell to:
-obtain what is needed from IF
-Keep out what it does not need

16

Membrane Transport

Plasma membranes selectively permeable
-some molecules pass through easily; some do not
Two ways substances cross membrane
-Passive processes
-Active processes

17

Passive Processes

-No cellular energy required
-Substance move down concentration gradient
-Diffusion (2)
-Osmosis

18

Diffusion

Molecules to move down or with their concentration gradient (speed of movement is determined by molecule size and temperature
Molecule will passively diffuse through membrane if:
-lipid soluble
-small enough to pass through membrane channels
-assisted by carrier molecule

19

3 Types of Diffusion
(Look at Diagram Cards)

-Simple Diffusion
-Carrier and Channel Mediated Facilitated Diffusion
-Osmosis

20

Simple Diffusion

Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through phospholipid bilayer
EX. oxygen, carbon dioxide, fat-soluble vitamins

21

Carrier-Facilitated Diffusion

Certain lipophobic molecules transported passively by;
-binding to protein carriers
-moving through water-filled channels
Transmembrane integral proteins are carriers
Used when sugars are too large for channels

22

Channel-Facilitate Diffusion

Watery channels formed by transmembrane proteins
Selectively transport ions or water
Two types:
-Leakage (always open)
-Gateway (controlled by chemical or electrical signals)

23

Osmosis

Water moves through:
-lipid bilayer
-specific water channels
Occurs when either water or solvent is too high on one side or the other than either:
-through impermeable;
osmosis occurs until equilibrium reached
-through permeable;
both solutes and water across membrane until equiilibrium reached

24

Pressures of Osmosis

Hydrostatic: back pressure of water on membrane
Osmotic: tendency of water to move into cell by osmosis

25

Importance of Osmosis
(Look at Diagram Cards)

Causes cells to swell and shrink
change in cell volume disrupts cell function, especially in neurons

26

Tonicity

Ability of solution to alter cell's water volume
3 tonics- iso, hyer, hypo

27

Isotonic

Solution with same non-penetrating solute concentration as cytosol

28

Hypertonic

Solution with higher non-penetrating solute concentration than than cytosol

29

Hypotonic

Solution with lower non-penetrating solute concentration than cytocol

30

Active Processes
2 Types

Requires ATP to move solutes across a plasma membrane because:
-Solute too large for channels
-Solute not lipid soluble
-Solute not able to move down concentration
Two types
-Active Transport
-Vesicular Transport

31

Active Transport

Requires carrier proteins to move solutes against concentration gradient
Requires energy (ATP)
Energy stored in ionic gradients used indirectly to drive transport of other solutes
Most common is Sodium Potassium Pump

32

Sodium Potassium Pump
(Look at Diagram Cards)

Carrier (pump) called Na+-K+ ATPase, located in plasma membranes
Na+ and K+ channels allow slow leakage down concentration gradients
Na+-K+ pumps works as exchanger
-pumps against Na+ and K+
-high intracellular K+ concentration
-high extracellular Na+ concentration
Maintains electrochemical gradients for function of muscle and nerve tissues
Allows all cells to maintain fluid volume

33

Vesicular Transport

Transport of large particles, macromolecules, and fluids across membrane in membranous sacs called vesicles
-Requires energy (ATP)
4 Functions:
-Exocytosis
-Endocytosis
-Transcytosis
-Vesicular Trafficking

34

Endocytosis

Transport into a cell
protein-coated vesicles
Some pathogens also hijack for transport into cell
Once vesicle is inside cell it may:
-fuse with lysosome
-undergo transcytosis

35

Exocytosis

Transport out of a cell
Usually activated by cell-surface signal or change in membrane voltage
Substance enclosed in secretory vesicle
Functions:
-Hormone secretion
-Neurotransmitter release
-Mucus secretion
-Ejection of wastes

36

Transcytosis

Transport into, across, and then out of a cell

37

Vesicular Trafficking

Transport from one area or organelle in cell to another

38

Resting Membrane Potential (RMP)

-Produced by separation of oppositely charged particles (voltage) across membrane in all cells
-Voltage (electrical potential energy) only at membrane

39

Electochemical Gradient

electro (charge); chemical (ion concentration)
K+ diffuses out of the cell through K+ leakage channels and so inside cell membrane more negative
K+ attracted back
K+ equalizes across membrane at -90mV when K+ concentration gradient balanced by electrical gradient =RMP

40

Cytoplasm

Located between the plasma membrane and nucleus
Made of
-Cytosol- water with proteins, salts, and sugars
-Organelles-cell parts with their individual function

41

Membranous

Rigid with a direct flow
-Mitochondria
-Peroxisomes
-Lysosomes
-Endoplasmic Reticulum
-Golgi Apparatus

42

Nonmembranous

Free floating
-Cytoskeleton
-Centrioles
-Ribosomes

43

Mitochondria

-Double membrane structure
-Breaks down food; turns into energy
-Power house

44

Ribosomes

Makes proteins with RNA
Protein Synthesis
2 types:
-Free
-Membrane-bound

45

Endoplasmic Reticulum

Two types:
Rough ER
Smooth ER

46

Rough Endoplasmic Reticulum

Packages proteins, and sends them to the Golgi Apparatus

47

Smooth Endoplasmic Reticulum

Provides Enzymes to:
-Absorb and transport fats
-Metabolic purposes
-Storage of calcium

48

Golgi Apparatus

Membranous Sacs
-Modifies, concentrates, and packages proteins and lipids from rough ER

49

Peroxisomes

Detoxifies harmful or toxic substances
-Neutralize dangerous free radicals

50

Lysosomes

Destroys cells in injured or non-useful tissue
Contains digestive enzymes

51

Endomembrane

Inside membrane of the cell
Includes:
-ER
-Golgi Apparatus
-Secretory vesicles
-lysosomes
-nuclear and plasma membranes

52

Cytoskeleton

Cells skeleton
-protects the cell from being squished
-structure for the cell
Includes
-micro-filaments
-intermediate filaments
-microtubules

53

Centrosomes and Centrioles

Cell center near nucleus
organizes mitotic spindles

54

Cilia and Flagella

Cell Extensions
-contains support structure
-moves substances across the cell surface

55

Microvilli

Cell Extension
-increases surface area for absorption

56

Nucleus

Nucleus has DNA (blueprint) for making proteins
Responds to signals

57

Nuclear Envelope

Double Membrane barrier
Protects Nucleus by allowing some substances to pass

58

Nucleoli

-Within Nucleus
-rRNA synthesis
-Contains DNA coding for rRNA

59

Chromatin

Threadlike strands of DNA, histone proteins, and RNA
Condenses into barlike bodies called chromosomes when cell starts to divide

60

Cell Cycle

Changes the formation of the cell until it reproduces.
2 parts
Interphase
Mitotic Phase

61

Interphase

Cell grows and carries out functions
-Period from cell formation to cell division
-Nuclear material called chromatin
-Adulthood of a cell

62

Cell Division (Mitotic Phase)

Divides into 2 cells

63

DNA Replication

Prior to division cell makes copy of DNA
The DNA helix splits and enzymes add nucleotides.
End result: two identical DNA molecules
-Copy given to new cell
-Initial DNA is retained in original cell

64

Meiosis

Cell divides in half
Ex. Egg and Sperm

65

Mitosis

Clone
Division of nucleus
Used for growth and tissue repair

66

Control of Cell Division

"GO" signal
-Cell grows to large so either divide or die
-Need to grow for body to grow
-They want contact so grow and divide so they touch and fill space

67

Protein Synthesis

DNA is mater blueprint for protein synthesis
Gene-segment of DNA with blueprint for ONE polypeptide

68

Role of RNA in Protein Synthesis

DNA decoding mechanism and messenger
Three types
-Messenger RNA (mRNA)
-Ribosomal RNA (rRNA)
-Transfer RNA (tRNA)

69

Difference between RNA and DNA

Uracil is substituted for Thymine

70

Messenger RNA

Carries instructions for building for building polypeptide
-From gene in DNA
-To ribosomes in cytoplasm

71

Ribosomal RNA

Structural component of ribosomes
-Helps translate message from mRNA

72

Transfer RNA

-Bind to amino acids
-Begin process of protein synthesis
-Makes proteins

73

Two Steps for Protein Synthesis

Transcription
Translation

74

Transcription

Copy
Transcription Factors: to make mRNA
Loosens DNA in area to be transcribed
Makes a template strand
RNA polymerase directs this process
-Enzyme making it happen

75

Translation

Decodes
Converts base sequence of nucleic acids into amino acid sequence of proteins
Involves all forms of RNA

76

Rough ER in Protein Synthesis

Forming protein enters ER
Protein enclosed in vesicle for transport to Golgi Apparatus

77

Summary: From DNA to Proteins

Complementary base pairing directs transfer of genetic information in DNA into amino acid sequence of protein
-DNA-mRNA
-Complementary base pairing of mRNA with tRNA ensures correct amino acid sequence
-This sequence is identical to DNA sequence except uracil substituted for thymine

78

Extracellular Materials

Body fluids- interstitial fluid, blood plasma, cerebrospinal fluid
Cellular Secretions- intestinal and gastric fluids, saliva, mucus, and serous fluids

79

Developmental Aspects of Cells

All cells of body contain same DNA but cells not identical
Chemical signals turn some genes on and others off
Development of specific and distinctive features in cells called Cell Differentiation

80

Apoptosis

-During development more cells than needed produced
-Eliminated later by programmed cell death
Birth
-Organs well formed and functional before birth
Adulthood
-Cell division to replace short-lived cells and repair wounds

81

Hyperplasia

Increases cell numbers when needed

82

Atrophy

decreased size, results from loss of stimulation or use