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A&P Section 1 > Chapter 3 > Flashcards

Chapter 3 Flashcards

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1
Q

What are the functions of the plasma membrane

A

Physical isolation: separating the cytoplasm from extracellular fluid
Regulation/exchange: plasma membrane acts as a gate keeper control entry of ions and nutrients, waste elimination, and release of secretions.
Sensitivity to environment: receptors sense changes in environment and respond accordingly.
Structural support: give tissue stability, for example, the cells at the surface of the skin are tightly bound together, while those in the deepest layers are attached to extracellular protein fibers in underlying tissues.

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2
Q

Anchoring protein

A

attaches the plasma membrane to other structures and stabilizes its position

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3
Q

Recognition protein

A

cells of the immune system recognize other cells as normal or abnormal based on the presence or absence of characteristic recognition proteins. Many are glycoproteins.

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4
Q

Enzymes

A

may be integral or peripheral proteins. Catalyze reactions in extracellular fluid or in the cytosol.

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5
Q

Receptor protein

A

sensitive to the presence of specific extracellular molecules called ligands (small ion to complex hormone)

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6
Q

Carrier protein

A

bind solutes and transport them across the plasma membrane.

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7
Q

Channel protein

A

or central pore that forms a passageway completely through the plasma membrane. The channel permits water and small solutes to move across the plasma membrane. Ions and other small water soluble materials can cross the membrane only by passing through channels.

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8
Q

Carbohydrates of plasma membrane

A

part of proteoglycans, glycoproteins, and glycolipids. Forms layer called glycocalyx.
Functions: lubrication, specificity of binding, and recognition

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9
Q

Differences between cytosol and extracellular fluid

A

[K] is much higher in the cytosol, [Na] is much lower
Cytosol has higher concentration of suspended proteins
Cytosol contains small quantities of carbohydrates and small reserves of A.A.

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10
Q

Organelles

A

structures suspended within the cytosol that perform specific functions of the cell.

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11
Q

Name the non-membranous organelles

A

Cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes

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12
Q

Name the membranous organelles

A

Golgi apparatus, lysosomes, peroxisomes, ER, and mitochondria

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13
Q

Microvilli

A

Extension of the plasma membrane containing microfilaments.

Increase surface area to facilitate absorption of extracellular materials

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14
Q

Centrosome and Centrioles

A

Cytoplasm contains two centrioles composed of 9 microtubules in 9+0 array.
Essential for movement of chromosomes during cell division; organization of microtubules in cytoskeleton

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15
Q

Cytoskeleton

A

Proteins organized in fine filaments or slender tubules.

Strength and support; movement of cellular structures and materials

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16
Q

Plasma membrane

A

Lipid bilayer containing phospholipids, steroids, and carbohydrates.
Isolation, protection, sensitivity, support, and controls entry and exit of materials.

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17
Q

Cilia

A

Long extensions of the plasma membrane containing microtubules; primary and motile.
A primary cilium acts as a sensor. Motile cilia move materials over cell surafaces

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18
Q

Proteasome

A

Hollow cylinders of proteolytic enzymes with regulatory proteins at their ends.
Breakdown and recycling damaged or abnormal intracellular proteins

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19
Q

Ribosomes

A

RNA + proteins; fixed ribosomes bound to rough ER; free ribosomes scattered in cytoplasm.
Protein synthesis

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20
Q

Lysosomes

A

Vesicles containing digestive enzymes.

Intracellular removal of damaged organelles or pathogens

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21
Q

Lysosomes

A

Vesicles containing digestive enzymes.

Intracellular removal of damaged organelles or pathogens

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22
Q

Golgi apparatus

A

Stacks of flattened membranes (cisternae) containing chambers.
Storage, alteration, and packaging of secretory products and lysosomal enzymes

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23
Q

Mitochondria

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A

Double membrane, with inner membrane folds (cristae) enclosing important metabolic enzymes.
Produce 95% of the ATP required by the cell

24
Q

Endoplasmic reticulum (ER)

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A

Network of membranous channels extending throughout the cytoplasm.
Synthesis of secretory products; intracellular storage and transport; detoxification of drugs or toxins
Rough ER: modifies and packages newly synthesized proteins
Smooth ER: synthesizes lipids and carbohydrates

25
Nucleoli
Nuclear organelles that synthesize ribosomal RNA
26
Nucleoli
Nuclear organelles that synthesize ribosomal RNA
27
Histones
RNA, enzymes, and proteins that compose the nucleoli
28
Nucleosome
DNA wound around histone
29
Chromatin
found in non-dividing cells
30
Chromosomes
tight coiling that occurs just before cell division
31
Process of protein synthesis
Transcription: 1)DNA strands separate and RNA polymerase binds to the promoter of the gene. 2)RNA polymerase moves from one nucleotide to another on the template strand. RNA nucleotides form H bonds with DNA nucleotides and the RNA polymerase then strings the arriving nucleotides together into mRNA. 3)At the stop signal, RNA polymerase and mRNA strand detach and the two DNA strands associate. Translation: 1)Initiation: mRNA strand binds to small ribosomal subunit at start codon. Attachment of tRNA and subsequent binding of large ribosomal subunit creates functional ribosomal unit. 2)Elongation: a.a. are added one by one. tRNA binds at the A site, the ribosome removes the a.a. and from the tRNA at the P site and attaches to the one at A site via peptide bond. Then the tRNA moves to the E site and is released into cytoplasm. 3)Termination: Elongation ends when a stop codon is reached. The mRNA strand remains intact and can interact with other ribosomes to create additional copies of the same chain.
32
Process of protein synthesis
Transcription: 1)DNA strands separate and RNA polymerase binds to the promoter of the gene. 2)RNA polymerase moves from one nucleotide to another on the template strand. RNA nucleotides form H bonds with DNA nucleotides and the RNA polymerase then strings the arriving nucleotides together into mRNA. 3)At the stop signal, RNA polymerase and mRNA strand detach and the two DNA strands associate. Translation: 1)Initiation: mRNA strand binds to small ribosomal subunit at start codon. Attachment of tRNA and subsequent binding of large ribosomal subunit creates functional ribosomal unit. 2)Elongation: a.a. are added one by one. tRNA binds at the A site, the ribosome removes the a.a. and from the tRNA at the P site and attaches to the one at A site via peptide bond. Then the tRNA moves to the E site and is released into cytoplasm. 3)Termination: Elongation ends when a stop codon is reached. The mRNA strand remains intact and can interact with other ribosomes to create additional copies of the same chain.
33
Diffusion
Passive and random across membrane from high concentration to low concentration. Effected by distance, molecule size, temperature, concentration gradient, and electrical forces
34
Simple diffusion
Alcohol, fatty acids, and steroids can enter easily because they diffuse through lipid portions of the membrane
35
Osmosis
Net diffusion of water across a selectively permeable membrane. Water flows towards the solution that has the higher concentration of solutes.
36
Carrier mediated transport
Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane. All types have specificity, saturation limits, and regulation similar to enzymes.
37
Types of Carrier mediated transport proteins
Cotransport (symport): two substances are transferred in the same direction at the same time Countertransport (antiport): one substance moves into the cell and the other moves out Facilitated diffusion: passively transports substances that are too large to fit through membrane channels. Substance binds to a receptor site on the carrier protein Active transport: a high energy bond provides ATP to move ions or molecules across the membrane. Does not depend on concentration gradient for movement. Ion pumps actively transport the cations (Na+), (K+), (Ca+), and (Mg+). Specialized cells can also transport (I-), (Cl-), and (Fe+). If countertransport occurs it's called an exchange pump.
38
Sodium-potassium exchange pump
Uses ATP to transport 3 sodium out of the cell and 2 potassium into the cell.
39
Secondary active transport
Does not directly require ATP. While one substance provides the driving force, the second substance hitches a free ride.
40
Vesicular transport
Materials move into or out of the cell in small membranous sacs called vesicles, or fuse with the plasma membrane
41
Endocytosis
Endocytosis: movement of relatively large volumes of extracellular material into the cytoplasm by formation of membranous vesicle at the cell surface receptor mediated endocytosis: vesicle-mediated movement into the cytoplasm of specific target molecules (ligands) Pinocytosis: vesicle-mediated movement of extracellular fluid Phagocytosis: vesicle-mediated movement of extracellular solids, especially bacteria and debris
42
Exocytosis
The ejection of cytoplasmic materials by the fusion of a membranous vesicle with the plasma membrane
43
Explain the origin and significance of transmembrane potential
The cells interior is slightly negative and the interior is slightly positive. The plasma membrane keeps the charged particles apart causing a potential difference which is known as the transmembrane potential (membrane potential). Typical membrane potential of cells is 70mV. It creates potential energy or stored energy that can be released to do work.
44
Describe the cell life cycle
* G1: Cell enters this phase when it's ready to divide. Normal cell functions plus growth, duplication of organelles, protein synthesis (8+ hours) * S: DNA replication, synthesis of histones (6-8 hours) * G2: Protein synthesis and completion of centriole replication (2-5 hours) * M: mitosis and cytokinesis (1-3 hours) * G0: Not preparing for division but is performing all the other functions. Some remain in this phase and will never divide such as skeletal muscle cells and neurons. Some cells that divide rapidly such as stem cells will never enter this phase.
45
What is the significance of mitosis
the end result of two identical daughter cells
46
What are the phases of mitosis
P-mat | Prophase, metaphase, anaphase, telophase
47
Early prophase
Chromosomes coil very tightly, spindle fibers extend between centriole pairs, and astral rays radiate into the cytoplasm.
48
Late prophase
There are two copies of DNA from S phase, each one called a chromatid connected to it's duplicate copy at the centromere. Kinetochores attach to spindle fibers forming chromosomal microtubules.
49
Metaphase
begins as chromatids move to the metaphase plate. Ends when all the chromatids are aligned at the plate
50
Anaphase
beings when the centromere of each chromatid pair splits and the chromatids separate. Daughter chromosomes are pulled towards opposite ends of the cells.
51
Telophase
each new cell prepares to return to the interphase state. Nuclear membranes re-form, nuclei enlarge and chromosomes gradually uncoil. This is the end of mitosis.
52
Cytokinesis
division of the cytoplasm into two daughter cells. Completion of this step marks end of cell division.
53
Regulation of cell life cycle
M-phase promoting factor (MPF): important internal trigger. Assembled from Cdc2 and cyclin. When MPF appears in the cytoplasm mitosis gets underway. Growth factors: natural body substances, such as hormones, peptides, or nutrients that can stimulate division of specific cells. Repressor genes: inhibit cell division. Once example is p53 which synthesizes a protein that binds to DNA to promote production of growth-inhibiting factors inside the cell. Roughly half of all cancers are associated with abnormal forms of p53 gene.
54
Relationship between cell division and cancer
Tumor: formed when rates of cell division exceed rates of cell death. Cancer: illness that results from abnormal proliferation of any of the cells in the body. Mutations disrupt the normal cell regulatory controls and produce potentially malignant cells.
55
Define differentiation
development of specific cellular characteristics and functions that are different from the original cell
56
What is the importance of differentiation
Produces specialized cells with limited capabilities. | Cells form organized collections known as tissues with discrete functional roles.

A&P Section 1 (3 decks)

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