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A&P Chapter 3 Flashcards

1
Q

Cell Theory

A

A cell is the smallest unit of life.
Cells can arise only from other preexisting cells.
All organisms are made up of one or more cells.

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2
Q

A human cell has 3 main parts:

A

Nucleus (DNA containing control center)
Plasma Membrane (flexible outer boundary)
Cytoplasm (intracellular fluid containing organelles)

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3
Q

Major classes of extracellular materials:

A
  1. Extracellular fluids:
    (A)Interstitial fluid (cells are submersed in this fluid)
    (B) Blood plasma (fluid of the blood) (C)Cerebrospinal fluid (fluid surrounding nervous system organs)
  2. Cellular secretions (saliva, mucus)
  3. Extracellular matrix (acts as glue to hold cells together)
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4
Q

Plasma membrane

A

Acts as an active barrier separating intracellular fluid from extracellular fluid.

Plays a role in cellular activity by controlling what enters and what leaves cells.

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5
Q

What is the phospholipid bilayer?

What is it made up of?

A

What the plasma membrane is made up of. Consists of phospholipids and small amounts of cholesterol. Has a polar hydrophilic head (on both inner and outer surface of membrane) and nonpolar hydrophobic tails (line the center of the membrane).

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6
Q

What does cholesterol do for the plasma membrane?

A

Cholesterol stiffens the plasma membrane by wedging its platelike hydrocarbon rings between phospholipid tails.

It also further decreases the water solubility of the membrane.

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7
Q

Glycocalyx

A

Carbohydrates on the outer portion of the plasma membrane form the glycocalyx, a carbohydrate-rich area created by glycoprotein and glycolipid sugars. This sugar coats cells.

The glycocalyx allows cells to recognize each other. It also allows inmunes cells to recognize friend vs foe.

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8
Q

Tight Junctions

A

In tight junctions, protein molecules in adjacent cells’ plasma membranes fuse together like a zipper forming an impermeable junction. This junction encircles the cell. These junctions restrict molecules from passing between cells.

Examples of tight junctions are found in the epithelial cells of the digestive tract.

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9
Q

Desmosomes

A

Anchoring junctions.
Bind adjacent cells together like molecular Velcro.
Desmosomes help keep cells from tearing apart.
Eg. Skin cells and heart muscle cells.

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10
Q

Gap Junctions

A

Cells are connected by hollow cylinders made of transmembrane proteins.

Gap junctions determine what can pass from 1 cell to its neighbor.

Eg. electrically excitable tissues like the heart.

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11
Q

Membrane proteins

What do they do?

What are the 2 types of membrane proteins?

A

Many roles:
Transport, communication, joining cells to each other and to the extracellular matrix.

Proteins are responsible for most specialized plasma membrane functions.

2 types (1) integral proteins (2) peripheral proteins

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12
Q

Integral Proteins

A

These are a type of plasma membrane protein.

Integral proteins are inserted into the lipid bilayer.

Integral proteins have both hydrophobic and hydrophilic regions. Some form channels or pores to bypass the lipid part of the plasma protein. Others act as carriers that bind to substances then move substances through the membrane.

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13
Q

Peripheral proteins

A

Either attach loosely to the integral proteins or have a hydrophilic region that anchors them into the membrane.

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14
Q

What are the 2 types of passive membrane transport and what type of energy does it use?

A

(1) - Diffusion
(2) - Filtration - usually occurs across capillary walls

Requires no energy

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15
Q

Simple diffusion

A

Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through the phospholipid bilayer. Eg. O2, co2, fat soluble vitamins

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16
Q

Facilitated diffusion
Certain hydrophobic molecules (glucos, amino acids, ions) are transported passively down their concentration gradients by…

A

1) Carrier mediated facilitated diffusion (substances bind to protein carriers)
2) Channel mediated facilitated diffusion (substances move through water-filled channels called aquaporins). (a)Leakage channels - always open (b) Gated channels - controlled by chemical or electrical signals.

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17
Q

Osmosis

A

Movement of solvent such as water, across the selectively permeable membrane.
Flow occurs when water (or other solvent) concentration is different on the two sides of a membrane.

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18
Q

Osmolarity

A

Is a measure of the total concentration of solute particles.

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19
Q

Hydrostatic pressure

A

Movement of water via osmosis causes pressure that drives fluid out.

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20
Q

Osmotic pressure

A

Osmosis (movement of water) causes this pressure, where the water has a tendency to move into cell by osmosis (the more solutes inside the cell, the higher the osmotic pressure).

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21
Q

Tonicity

A

Ability of a solution to change the shape or tone of cells by altering the cells’ internal water volume.
Isotonic solution, hypertonic solution or hypotonic solution.

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22
Q

Isotonic solution

A

Cells retain their normal size and shape in this solution (same solute/water concentration inside as well as outside of the cell; water moves in and out).

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23
Q

Hypertonic solution

A

Cells lose water by osmosis and shrink in this solution (contains a higher concentration of solutes than are present inside the cell). Water leaves the cell.

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24
Q

Hypotonic solution

A

Cells take on water by osmosis until the become bloated and burst (lyse) in this solution (contains a lower concentration of solutes than are present inside the cell).

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25
Q

Reasons for active membrane transport

A

Solute is too large for channels,
Solute is not lipid soluble, or
Solute is not able to move down concentration gradient.

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26
Q

Active transport

A

Requires carrier proteins (solute pumps) which bind with the substance being moved. Moves solutes against their concentration gradient (from low to high). Requires ATP

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27
Q

Antiporters

A

Transport one substance into cell while transporting a different substance out of cell (substances “wave to each other”)

28
Q

Symporters

A

In active transport, symporters transport 2 different substances in the same direction.

29
Q

2 types of active transport are:

A

Primary active transport
Secondary active transport

Both require carrier proteins.

30
Q

primary active transport

A

The energy required for this transport comes directly from ATP hydrolysis.
The transfer (carrier) protein changes its shape so that it pumps the bound solute across the membrane.

31
Q

Secondary active transport: Where does its energy come from?

A

The required energy for secondary active transport is obtained indirectly from ionic gradients created by primary active transport.

Secondary active transport uses the “down the gradient” movement of one solute to create the “up the gradient” movement of another solute.

Requires carrier proteins.

32
Q

Vesicular Transport

A

Involves transport of large particles, macromolecules and fluids across the membrane in membranous sacs called vesicles.
Requires ATP / cellular energy

33
Q

What are the 4 vesicular transport processes:

A

Endocytosis
Exocytosis
Transcytosis
Vesicular trafficking

34
Q

Endocytosis: what does it do and what are the 3 types of endocytosis?

A

Transport into the cell. Relies on receptors in the membrane to determine the substances to be transported.
3 different types of endocytosis (1) phagocytosis (2) pinocytosis (3) receptor-mediated endocytosis

35
Q

Phagocytosis

A

“Cell eating”
Phagocytes ingest and dispose of bacteria, foreign substances and dead tissue cells. Eg. WBCs

36
Q

Pinocytosis

A

“Cell drinking”
Aka fluid-phase endocytosis
Vesicles surround extracellular fluid containing dissolved molecules. Vesicle enters the cell and fuses with a sorting versicle.

37
Q

Receptor-mediated endocytosis

A

A cell’s receptors are plasma membrane proteins that bind only certain substances (ligands). The receptors and attached molecules become internalized.

38
Q

Exocytosis

A

Vesicle transport processes that eject substances from the cell interior to the extracellular fluid.

39
Q

Transcytosis

A

Transports into, across and then out of the cell.

40
Q

Vesicular trafficking

A

Transport from one area or organelle in the cell to another.

41
Q

CAMs (cell adhesion molecules)

A

Sticky glycoproteins
CAMs are the molecular Velcro cells use to anchor themselves to extracellular molecules.

CAMs are the arms that migrating cells use to hand themselves past one another.

SOS signals

CAMs transmit information about changes in extracellular matrix into the cell, bringing about cellular responses.

42
Q

Roles of Plasma Membrane Receptors

A

Integral proteins that serve as binding sites.

Contact signaling: Cells come together and touch / recognize each other.

Chemical signaling: interaction between receptors and ligands [chemical messengers] that cause changes in cellular activities.

43
Q

Cytoplasm is composed of:

A

Cystol - gel-like solution made up of water and soluble molecules such as proteins, salts, sugars, etc.
Inclusions - insoluble molecules; vary with cell type
Organelles - metabolic machinery structures of cell; each with specialized function

44
Q

Membranous Organelles
Membranes allow compartmentalization which is crucial to cell functioning.

A

Mitochondria
Endoplasmic reticulum
Golgi apparatus
Peroxisomes
Lysosomes

45
Q

Nonmembranous organelles

A

Ribosomes
Cytoskeleton
Centrioles

46
Q

Mitochondria

A

Threadlike / Lozenge shaped and membranous

Provide most ATP supply to the cell.

Cristae - are embedded with membrane proteins that play a role in cellular respiration.

Mitochondria contain their own DNA, RNA and ribosomes
Resemble bacteria; capable of same type of cell division bacteria use called fission (where they pinch in half).

47
Q

Ribosomes

A

Nonmembranous organelles that are the site of protein synthesis.

Synthesizes proteins for incorporation into the cell membranes, or lysosomes, or for export from the cell.

Made up of protein and ribosomal rRNA

48
Q

Rough ER

A

Series of interconnected cisterns. Surface is studded with ribosomes.

Its ribosomes manufacture all proteins that are secreted from cells. It also produces the proteins and lipids that form membranes for the cell parts (cell’s membrane factory).

49
Q

Smooth ER

A

Consists of tubules and is continuous with the rough ER

It’s enzymes catalyze reactions involved with a number of processes.

50
Q

Golgi Apparatus

A

Stacked and flattened membranous sacs shaped like hollow dinner plates; tiny membranous vesicles.

Modifies, concentrates and packages proteins and lipids that came from the rough ER.

Golgi is the cell’s “traffic director”.

51
Q

Peroxisomes

A

Membranous sacs containing powerful detoxifying substances that neutralize toxins.
Free radicals: toxic, highly reactive molecules that are natural by-products of cellular metabolism; can cause havoc to cell if not detoxified.
2 main detoxifiers (1) oxidase uses oxygen to convert toxins to hydrogen peroxide h2o2, which is itself toxic; however, Peroxisomes also contains (2) catalase which converts h2o2 to harmless water.

Peroxisomes also play a role in the breakdown and synthesis of fatty acids.

52
Q

Lysosomes

A

Membranous bags containing digestive enzymes

Digest bacteria, toxins, etc. Break down non functioning organelles. Cause injured cells to digest themselves.

53
Q

Cytoskeleton

A

Network of rods that exist in cytosol, plus accessory proteins that link the rods to other cell structures.

Nonmembranous

Plays a role in movement of cell parts by acting as cells’ bones, ligaments and muscles. Helps maintain cell structures.

3 types:
Microfilaments, Intermediate filaments, Microtubules

54
Q

Centrosome & Centrioles

A

Centrosome: the cell center where microtubules are centered near the nucleus.
Acts as a microtubules organizing center.

Some microtubules aid in cell division, some form cytoskeleton track system.

Centrioles - small barrel-shaped organelles oriented at right angles to each other. Centrioles form the basis of cilia and flagella.

55
Q

Cilia and flagella

A

These are structures that extend from the cell surface.
They aid in the movement of the cell or of materials across the surface of the cell.
Cilia: whiplike motile cellular extensions that typically occur in large numbers.
Eg: ciliated cells that line the respiratory tract propel mucus laden with particles upward and away from the lungs.

Flagella are also projected from centrioles, but are substantially longer than cilia. The flagellum propels the cell itself.

56
Q

Microvilli

A

Finger like projections that extend from the surface of the cell to increase surface area.

57
Q

Nucleus

A

Contains the instructions (nuclear DNA) needed to build nearly all the body’s proteins.

The cell control center. Responds to signals that dictate the kinds of proteins required to be synthesized.

58
Q

The nucleus has 3 main structures:

A

Nuclear envelope
Nucleoli
Chromatin

59
Q

The nuclear envelope

A

Is a double membrane with nuclear pores.

The outer layer is continuous with the rough ER and, like the rough ER, is studded with ribosomes. The inner layer of the nuclear envelope, called the nuclear lamina, is a network of mesh proteins that maintains nuclear shape and acts as scaffolding for DNA

The nuclear envelope encloses a jelly-like fluid called nucleoplasm.

60
Q

Nuclear Pores

A

Puncture the nuclear envelope.
Each pore is lined by an intricate complex of proteins which form an aqueous transport channel and regulate entry and exit of molecules and large particles into and out of the nucleus.

61
Q

Nucleoli

A

Dark staining spherical bodies within the nucleus.
Nucleoli are not membrane bound.
Nucleoli are involved in ribosomal RNA synthesis and ribosome subunit assembly.
Usually there are one or 2 nucleoli per cell.

62
Q

Chromatin

A

Chromatin refers to a mixture of DNA and proteins that form the chromosomes found in cells.

Chromatin is part Threadlike strands of DNA + part histone proteins.

63
Q

Diffusion

A

The movement of molecules or ions from an area where they are in high concentration to an area where they are in lower concentration.

64
Q

Microfilaments

A

Made of actin; cause cell movement or changes in cell shape (highly developed in muscle)

Cytoskeleton emelement.

65
Q

Intermediate filaments

A

Cytoskeletal element.

Made of tetramer fibrils; resemble woven ropes; Make cells stable, permanent, and strongly resist tension placed on the cell. These filaments are attached to desmosomes.

66
Q

Microtubules

A

(Cytoskeletal element)
Hollow tubes made of spherical protein subunits called tubulins; determine the overall shape of the cells as well as the distribution of cell organelles.
Motor proteins continually move and reposition organelles along the microtubules.

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