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Physiology (MPP 3202) > Ch. 3 Cell Structure and Genetic Control > Flashcards

Ch. 3 Cell Structure and Genetic Control Flashcards

1
Q

Understand and be able to ID cell parts

A
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2
Q

Cell Structure: Plasma Membrane

A

Selectively permeable, gives form, and separates from the external environment

ALL cells have plasma membrane; we have to be able to control what enters/exits the cell

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3
Q

Cell Structure: Cytoplasm and Organelles

A

Fluid part of cell and cellular functions; most of our body’s water is stored in cytoplasm

Organelles include things such as the Golgi complex, mitochondria, lysosomes…

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4
Q

Cell Structure: Nucleus

A

Contains DNA and directs cell activities

Some cells have multiple nuclei (skeletal muscle)

Some cells have NO nuclei (RBCs)

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5
Q

What structure is this?

A

Plasma Membrane

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6
Q

Plasma Membrane

A

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

–Hydrophobic center restricts movement of water, water-soluble molecules, and ions

–Some substances can selectively be allowed to pass through protein channels

–Proteins and phospholipids contantly move laterally - the fluid mosaic model

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7
Q

Plasma membrane: location of hydrophobic part and hydrophilic part

A

Hydrophobic part (fatty acid) tucked inside

Hydrophilic part (double layer) faces outside

Going to move water-soluble substances through the phospholipid barrier

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8
Q

Membrane Proteins

A

Integral Proteins: span the membrane (stuck/integrated in there)

Peripheral proteins are embedded on just one side of the membrane (associated w/ the phospholipid head)

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9
Q

Membrane Proteins: Fxns

A

Fxns:

–structural support

–transport

–enzymatic control of cell processes

–receptors for hormones and other molecules

–“self” markers for immune system

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10
Q

Other Membrane Components: CHO

A

Attached to lipids (glycolipids) and to proteins (glycoproteins); seve as antigens and interactions with regulatory molecules

Tells body which cells are “self”

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11
Q

Other Membrane Components: Cholesterol

A

Gives flexibility to the membrane

–as we age, our cells become stiff. Cholesterol helps keep cells flexible

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12
Q

What is this structure?

A

Cell membrane

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13
Q

What is phagocytosis?

A

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

Cell-eating

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14
Q

What is endocytosis?

A

The plasma membrane furrows inward rather than extending outward. 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.

Bringing something from outside to inside the cell

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15
Q

What is exocytosis?

A

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

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16
Q

What are cilia?

A

Tiny, hairlike structures composed of microtubules that project from the plasma membrane

ALL cells have cilia

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17
Q

What are primary cilium?

A

Most cells have this nonmotile cilium; may have a sensory function in some cells

–kidneys have primary cilium

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18
Q

What are motile cilia?

A

Beat in unison to move substances through hollow organs. Found in respiratory tract and uterine tubes

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19
Q

What are flagella?

A

A single whip-like structure that can propel a cell forward; sperm cells are the only cells that have flagella

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20
Q

What are these?

A

Both are cilia

Left is 9+2 arrangement; right (nonmotile cilia) is 9+0 arrangement

Motile: 9 pairs on outside, pair on inside

Nonmotile: lack pair on inside, still have 9 pairs on outside

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21
Q

What is this?

A

Microvilli

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22
Q

Microvilli

A

Folds in the plasma membrane that increase the surface area, found in intestines and kidneys

NOT found in endothelium of blood (they’re just transporters)

Important in intestines for absorption of nutrients

Important in kidneys to pull back water

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23
Q

Cytoplasm

A

Includes organelles, a fluid called cytosol, the cytoskeleton, and inclusions (stored chemical aggregates such as glycogen)

*Cytoplasm and cytosol are the same (just different terms used interchangeably)

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24
Q

Cytoskeleton

A

Organized system of microtubules and microfilaments throughout the cytoplasm

Organize the intracellular environment and alloow movement of muscle cells and phagocytic cells

Form spindle apparatus that pulls chromosomes apart in mitosis

They also facilitate vesicle and organelle movement in the cell

  • Actin (microfilaments)* - predominant one
  • Keratin (intermediate)*
  • Microtubules (cilia, flagella, microvilli)*
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25
Q

Cytoskeleton [in a nut shell]

A

Runs all throughout the cell; constant dymanic structure

Provides roadmap for where we need to move things throughout the cell

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26
Q

What is this?

A

Cytoskeleton

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27
Q

Lysosomes

A

Organelles filled with digestive enzymes (acidic)

–fuse w/ vacuoles after an immune cell engulfs a bacterium or dead cell

Membrane-bound organelle

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28
Q

Lysosome: Primary Lysosome

A

Only contains digestive enzymes

Waiting to do work

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29
Q

Lysosome: Secondary Lysosome

A

Contains the partially digested contents of the food vacuole or worn-out organelles

Doing work

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30
Q

Lysosome: Autophagy

A

Process of digesting damaged organelles and proteins in the cell

–degrading part of the cell, like those that have mistakes/are worn out

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31
Q

Lysosome: Apoptosis

A

Programmed cell death

“cell suicide”; does NOT cause inflammation

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32
Q

Necrosis

A

Cell blows up and releases lysosomes, leads to inflammatory response

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33
Q

Peroxisomes

A

Contain enzymes specific to certain oxidative reactions; degrade long-chain fatty acids and foreign molecules

Found in most cells but most numerous in liver; often oxidize toxic molecules (such as alcohol)

Generate hydrogen peroxide (H2O2)

–in the process of getting rid of toxic molecules, it generates a lot of hydrogen peroxide –> kills cells

34
Q

Mitochondria

A

Site of energy production through aerobic cell respiration

–powerhouse of cell, makes ATP

Central area is fluid and called the matrix

Most cells have mitochondria, and there can be thousands of mitochondria in a single cell (RBCs are an exception)

Mitochondria can migrate and replicate; they have their own DNA, all maternal-derived

–mitochondria passed on from mother ONLY

35
Q

Mitochondria: Structure

A

Have an inner membrane and an outer membrane separated by an intermembranous space

Inner membrane is folded into cristae to increase surface area for reactions

36
Q

What is this?

A

Mitochondria

37
Q

Ribosomes

A

Protein factories of the cell

Very small; made up of 2 subunits of ribosomal RNA and protein

Found free in the cytoplasm or associated with the endoplasmic reticulum

38
Q

Endoplasmic Reticulum (ER)

A

System of membranous passageways from the nuclear membrane to the plasma membrane

39
Q

Rough ER

A

Has ribosomes embedded on the outer surface, protein synthesis and modification

40
Q

Smooth ER

A

Has no ribosomes, synthesis of fatty acids, steroids, lipid

41
Q

Golgi Complex (Apparatus)

A

Consists of stacks of hollow, flattened sacs; cavities are called cisternae.

One side receives proteins from the ER, may modify proteins

Proteins are packaged in vesicles called endosomes, that bud off to fuse with the plasma membrane for exocytosis.

“Distribution center”

Membrane-bound organelles

Located close to rough ER, stacked to give itself a high membrane surface area

42
Q

Describe how proteins from the Rough ER get packaged and distributed.

A

Proteins made in Rough ER move to Golgi, get packaged into vesicles, sent to plasma membrane via cytoskeleton, then proteins get dumepd out by exocytosis

43
Q

Most cells have how many nuclei?

A

One

44
Q

How many nuclei do muscle cells have?

A

Hundreds

45
Q

How many nuclei do mature RBCs have?

A

None

46
Q

The nucleus is enclosed by the ____ ____ made up of two membranes.

A

Nuclear Envelope

47
Q

Describe the outer membrane of the nucleus

A

Continuous with the Rough ER

48
Q

Describe the inner membrane of the nucleus

A

Often fused to outer membrane by nuclear pore complexes, which allow small molecules and RNA to move into/out of the nucleus through pores.

Nuclear pore acts as a channel; targets what is allowed in/out of cell

49
Q

Nucleoli

A

The dark region not surrounded by a membrane, contains the DNA that codes for the production of ribosomal RNA.

50
Q

What is this entire structure?

A

Cell Nucleus

*You should be able to ID the nucleoli, inner membrane, outer membrane, and pore complex.

51
Q

What contains the DNA?

A

Nucleoli

52
Q

What is a gene?

A

A length of DNA that codes for a specific protein

53
Q

Describe genetic transcription

A

The gene on the DNA is transcribed as messenger RNA (mRNA)

DNA –> RNA (taking one nucleotide and making it into another)

54
Q

Describe genetic translation

A

mRNA is then translated at the ribosome to assemble the proper AA sequence.

Nucleotide –> AA (happens at ribosome)

55
Q

DNA in the nucleus is packaged with proteins called ____ to form ____.

A

Histones; Chromatin

56
Q

Why is DNA packaged?

A

It has to be packaged in order to fit in the cell

57
Q

Histones

A

Positively charged and will interact with negatively charged DNA to cause spooling

–creates particles called nucleosomes

58
Q

Euchromatin

A

Active in transcription, looser; chemical changes in histones (such as acetylation) allow molecules access to the DNA during gene expression

DNA that’s loose; actively being transcribed

59
Q

Heterochromatin

A

Inactive regions, highly condense; much of the DNA is inactive.

Often seen when you stain the nucleoli

60
Q

Transcription (RNA Synthesis)

A

Nucleotide to Nucleotide; how we make RNA

Start and stop regions at the beginning and end of the gene

Promoters, areas of DNA that are not part of the gene but signal enzymes involved where to begin transcription

Transcription factors that bind to the promoter to begin transcription

–piece of DNA (often bound by a protein called a transcription factor) tells us to turn the gene on

61
Q

Transcription (RNA Synthesis): RNA Polymerase

A

Breaks up the hydrogen bonds between the base pairs of DNA and assembles the appropriate RNA nucleotide

–RNA nucleotides pair up to the DNA template

Assembly is complementary. If DNA is CGTA, RNA will be GCAU

62
Q

RNA has ____ instead of thymine

A

Uracil

63
Q

In transcription, how many DNA strands are transcribed? What do those strands form?

A

1 strand is transcribed; form precursor mRNA

64
Q

pre-mRNA

A

Made directly by transcription

65
Q

mRNA

A

Messenger RNA

Modified pre-mRNA; contains the code to make a specific protein

66
Q

tRNA

A

Transfer RNA

Carries AA to mRNA for translation

67
Q

rRNA

A

Ribosomal RNA

Along with protein, forms ribosomes; site of translation; acts as an enzyme

68
Q

What are Introns?

A

Noncoding regions within gene; found on pre-mRNA

69
Q

What are Exons?

A

Coding regions

70
Q

Translation (Protein Synthesis)

A

mRNA attaches to a string of ribosomes to form a polyribosome (mRNA has to leave nucleus to associate w/ ribosome)

A group of three bases on DNA, called a triplet, gives the complementary three base sequence in mRNA, called a codon.

– 1 triplet yields 1 AA

The codon codes for an AA, so the order of the codons gives the order of AA in a polypeptide

–more codons exist than AAs (only 20 AAs)

71
Q

Transfer RNA

A

Single strand of RNA bent into a cloverleaf shape

One end has the anticodon, which is 3 nucleotides that will be complementary to the proper codon.

–anticodon reads codon that’s found on mRNA

The other end has the appropriate AA bonded by aminoacyl-tRNA synthetase enzyme

–reads mRNA and brings correct AA to peptide chain

72
Q

What is this process?

A

Translation

73
Q

Post-Translational Modification

A

Protein folding (chaperone proteins)

Cross-linkage (disulfide bonds)

Cleavage (to make active form… e.g. insulin)

Addition of other molecules or groups (phosphate, methyl)

Assembly into polymeric proteins

Lots of work to make proteins

74
Q

Describe DNA Replication

A
  1. Before cell division, each DNA molecule must replicate (DNA –> DNA)
  2. Involves many enzymes and proteins; two important enzymes are:
    a. 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
    b. DNA Polymerase attaches complementary nucleotides to the exposed strand
75
Q

What is this?

A

Mitosis

76
Q

What is the cell cycle divided into?

A

Interphase, Mitosis, and Cytokinesis

77
Q

Interphase

A

Divided into G1, S, and G2

78
Q

Mitosis

A

Divided into Prophase, Metaphase, Anaphase, and Telophase.

Gives us 2 indentical daughter cells w/ 23 pairs of chromosomes

79
Q

Cytokinesis

A

Overlaps the last part of mitosis

80
Q

What is this?

A

Meiosis

81
Q

What is Meiosis?

A

Process by which 2 cell divison steps produce gametes (ova and sperm); only occurs in gonads (ovaries and testes)

1st division: each of the daughter cells then has 23 (not 46) chromosomes, each consisting of 2 chromatids (duplicated chromosomes).

2nd division: chromatids separated. In ovaries, three of daughter cells die, only one becomes mature egg. In sperm, all 4 cells are functional.

Reduction to 23 chromosomes allows for sperm and egg to combine and “produce” 46 chromosomes.

82
Q

Where does Meiosis occur?

A

Reproductive organs

Physiology (MPP 3202) (32 decks)

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