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Physiology > Ch 3 > Flashcards

Ch 3 Flashcards

1
Q

Cell Structure

A
  1. Plasma membrane – selectively permeable, gives form, and separates from the external environment
    - ALL cells have this, separates individual units
  2. Cytoplasm and organelles – fluid part of cell and cellular functions
    - most of water stored here
    - golgi bodies, lysosomes, mitochondria, etc
  3. Nucleus – contains DNA and directs cell activities
    - “brain center”
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2
Q

Plasma Membrane

A

Phospholipid barrier (double layer) between the intracellular and extracellular environments

  • Hydrophobic center restricts the movement of water, water-soluble molecules, and ions
  • ->hydrophobic (inside, fatty acid tails) and hydrophilic (double-layer goes to outside)
  • Some substances pass through protein channels
  • Proteins and phospholipids constantly move laterally – the fluid mosaic model
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3
Q

Membrane Proteins

A

• Integral proteins- span the membrane (integrated into membrane)
• Peripheral proteins- embedded on just one side of the
membrane (associated with phospholipid head)
Functions:
• Structural support
• Transport
• Enzymatic control of cell processes
• Receptors for hormones and other molecules
• Self markers for the immune system

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4
Q

Other Membrane Components

A

Carbohydrates– attached to lipids (glycolipids) and to proteins (glycoproteins); serve as antigens and interactions with regulatory molecules

Cholesterol–gives flexibility to the membrane

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5
Q

Phagocytosis

A

IN
-Bulk transport or large extracellular substances into the
cell
-Important for body defense, inflammation, and apoptosis.

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6
Q

Endocytosis

A

IN

  1. The plasma membrane furrows INWARD rather than extending outward.
  2. A small part of the membrane surrounding the substance pinches off and is brought in as a vesicle.
    - May be mediated by a receptor, receptor-mediated endocytosis.
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7
Q

Exocytosis

A

OUT

Large cellular products (proteins) are moved out of the cell.

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8
Q

Cilia and types

A

tiny, hairlike structures composed of microtubules
that project from the plasma membrane
1. Primary cilium – most cells have this nonmotile cilium; may have a sensory function in some cells
2. Motile cilia- beat in unison to move substances through hollow organs. Found in respiratory tract and uterine tubes
–> motile: 9+2, nonmotile: 9+0

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9
Q

Flagella

A

a single whip-like structure that can propel a cell forward; sperm only

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10
Q

Microvilli

A

Projections off/folds in the plasma membrane that increase the surface area.
-important for absorption in intestines, reabsorb water in kidneys

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11
Q

Cytoplasm

A

Includes: organelles, a fluid called cytosol, the cytoskeleton, and inclusions (stored chemical aggregates such as glycogen).
–> may be interchangeable with “cytosol”

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12
Q

Cytoskeleton

A

“Road-map” and structural support

  • system of microtubules and microfilaments in cytoplasm
  • Organize the intracellular environment and allow movement of muscle cells and phagocytic cells
  • Form the spindle apparatus that pulls chromosomes apart in mitosis
  • facilitate vesicle and organelle movement in the cell
  • -> Actin (Microfilaments - predominant), Keratin (Intermediate), Microtubules (cilia, flagella, microvilli)
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13
Q

Lysosomes

A

Organelles filled with digestive enzymes (acidic)

-Fuse with vacuoles after an immune cell engulfs a bacterium or dead cell

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14
Q

Primary vs. Secondary Lysosome

A

Primary: only contains digestive enzymes (no work yet)
Secondary: contains the partially digested contents of the food vacuole or worn-out organelles (doing work)

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15
Q

Autophagy

A

process of digesting damaged organelles and proteins in the cell (w/mistake or worn out)

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16
Q

Apoptosis

A

programmed cell death

-cell suicide - engulf WHOLE cell away from within

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17
Q

Necrosis

A

blows cell up —> releases lysosomes —> inflammatory response

-different from apoptosis

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18
Q

Perioxisomes

A

Digestive, membrane-bound organelle

  • Contain enzymes specific to certain oxidative reactions; degrade long-chain fatty acids and foreign molecules
  • in most cells, LOTS in liver
  • generate hydrogen peroxide
  • must compartmentalize b/c if blown up would kill cell w/toxic H2O2
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19
Q

Mitochondria

A

“Powerplant”

  • site of energy production through aerobic cell respiration
  • Most cells have mitochondria, and there can be thousands of mitochondria in a single cell
  • Mitochondria can migrate and replicate; they have their own DNA, all maternal-derived
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20
Q

Mitochondria structure

A
  • inner membrane, outer membrane, inter membranous space
  • ->inner membrane is folded into cristae to increase surface area for reactions
  • central area = fluid called “matrix”
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21
Q

Ribosomes

A

Protein factories of the cell
-Very small; made of 2 subunits of ribosomal RNA
and protein
-Found free in the cytoplasm or associated with the endoplasmic reticulum

22
Q

Endoplasmic Reticulum (ER)

A

System of membranous passageways from the nuclear membrane to the the plasma membrane
-close to nucleus

23
Q

Rough vs. Smooth ER

A

Rough ER: has ribosomes embedded on the outer surface, protein synthesis and modification.

Smooth ER: has NO ribosomes, synthesis of fatty acids, steroids, lipids.

24
Q

Golgi Complex (Apparatus)

A
  • Consists of stacks of hollow, flattened sacs = increased SA
  • cavities are called cistern
  • one side receives proteins from the ER (close to rough ER), may modify proteins
  • -> proteins are packaged in vesicles called endosomes, that bud off to fuse with the plasma membrane for exocytosis
  • **sending it out to wherever it needs to be” = “Distribution Center”
25
Cell Nucleus
- most cells have 1, muscle cells have 100s, RBCs have none - enclosed by the nuclear envelope made of two membranes Nucleoli: dark region not surrounded by a membrane, contains the DNA that codes for the production of ribosomal RNA
26
Two membranes of nucleus
Outer membrane: continuous with rough ER Inner membrane: often fused to outer by nuclear pore complexes (which allow small molecules and RNA to move into/out of the nucleus through pores)
27
DNA
contained in the nucleus 1. the gene on the DNA is transcribed as messenger RNA (mRNA) – GENETIC TRANSCRIPTION 2. the messenger RNA is then translated at the ribosome to assemble the proper amino acid sequence – GENETIC TRANSLATION
28
Gene
a length of DNA that codes for a specific protein
29
Chromatin
—>How we package DNA - cannot be stored in long strands -DNA in the nucleus is packaged with proteins called histones to form chromatin -
30
Histones
positively charged and will interact with negatively charged DNA to cause spooling --> creates nucleosomes (DNA + protein + histone)
31
Euchromatin
- ACTIVE in transcription - looser - chemical changes in histones (such as acetylation) allow molecules access to the DNA during gene expression
32
Heterochromatin
- inactive regions --> much of the DNA is inactive | - highly condensed
33
Transcription (RNA Synthesis)
- Start and stop regions at the beginning and end of the gene - Promoters - Transcription factors - RNA Polymerase - DNA is GCTA, RNA is CGAU - Forms precursor messenger RNA that detaches from the DNA template - only 1 DNA strand is transcribed
34
Transcription (RNA Synthesis): Promoters
areas of DNA that are not part of the gene but signal | enzymes involved where to begin transcription
35
Transcription (RNA Synthesis): Transcription Factors
bind to the promoter to begin transcription
36
Transcription (RNA Synthesis): RNA polymerase
breaks the hydrogen bonds between the base pairs of DNA and assembles the appropriate RNA nucleotide -RNA nucleotides pair up to the DNA template
37
RNA Types
- Precursor messenger RNA (pre-mRNA) - Messenger RNA (mRNA) - Transfer RNA (tRNA) - Ribosomal RNA (rRNA)
38
Precursor messenger RNA (pre-mRNA)
made directly by transcription
39
Messenger RNA (mRNA)
modified pre-mRNA; contains the code to make a specific protein
40
Transfer RNA (tRNA)
carries amino acids to mRNA for translation --> turn nucleotide code to amino acid sequence, tRNA brings in AA •A single strand of RNA bent into a cloverleaf shape •One end has the anticodon, which is three nucleotides that will be complementary to the proper codon. •The other end has the appropriate amino acid bonded by aminoacyl-tRNA synthetase enzyme
41
Ribosomal RNA (rRNA)
along with protein, forms ribosomes - site of translation - acts as an enzyme - -> unique: ribosomal enzyme required for protein synthesis
42
Introns
noncoding regions within gene | -removed during mRNA synthesis/splicing
43
Exons
coding regions within gene
44
Translation (Protein Synthesis)
- mRNA attaches to a string of ribosomes to form a polyribosome - a group of three bases on DNA (triplet), gives the complementary three base sequence in mRNA (codon) - the codon codes for an amino acid, so the order of the codons --> the order of amino acids in a polypeptide
45
Post-Translational Modification
* Protein folding (chaperone proteins) * Cross-linkage (disulfidebonds) * Cleavage * Addition of other molecules or groups (phosphate, methyl) * Assembly into polymeric proteins
46
DNA Replication
1. Before cell division, each DNA molecule must replicate. 2. Involves many enzymes and proteins; two important enzymes are: a. Helicases b. DNA polymerase
47
Helicases
break hydrogen bonds between the DNA strands - This creates a fork in the double-stranded molecule where nucleotides can be added to both strands - -> two exact replicas of DNA strand
48
DNA polymerase
attaches complementary nucleotides to the exposed strand
49
Cell Cycle
• Divided into interphase, mitosis, and cytokinesis • Interphase is divided into G1, S, and G2 • Mitosis is divided into Prophase, Metaphase, Anaphase, and Telophase • Cytokinesis overlaps the last parts of mitosis • Produces 2 identical cells to parent cell with 46 chromosomes (23 pairs) -gives 2 identical cells w/22 pairs of chromosomes —> need to make IDENTICAL skin/gut/etc cells
50
Meiosis
-two cell division steps produce gametes (ova and sperm) -only occurs in the gonads (ovaries and testes) 1st Division: Homologous chromosomes line up side by side. One member of the pair is then drawn to each pole. Each daughter cell now has 23 (not 46) chromosomes, w/two chromatids (duplicated chromosomes). 2nd Divison: chromatids are separated * In the ovaries, three of the daughter cells die, only one becomes mature egg * Maternal and paternal members of homologous chromosome pairs are randomly shuffled; the daughter cells from first division have randomly derived chromosomes. * Reduction to 23 chromosomes allows for sperm and egg to combine and produce 46 chromosomes.

Physiology (29 decks)

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