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Berkeley MCAT Biology > Chapter 6 - Structure and Function in Cells and Viruses > Flashcards

Chapter 6 - Structure and Function in Cells and Viruses Flashcards

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1
Q

Glycerophospholipid

A

main component of all biological membranes, two fatty acid tails esterified to C1 and C2, with a phosphate group on C3, amphiphilic in nature

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2
Q

Sphingolipids

A

derivatives of amino alcohols, C2 carbon has amino group that can be linked to a FA via amide linkage (called a ceramide) structural residue that is common to all sphingolipids

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3
Q

Sphingomyelin

A

sphingolipid with a phosphoethanolamine or phosphocholine group on C1 of ceramide

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4
Q

Cerebroside

A

sphingolipid when a single monosaccharide is attached to C1 of ceramide

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5
Q

Gangliosides

A

several sugar residues are attached to C1 of the ceramide

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6
Q

Steroid Hormones

A
  1. Progesterone
  2. Glucocorticoids
  3. Mineralocorticoids
  4. Androgens
  5. Estrogens
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7
Q

Progesterone

A

function in women, prepares the uterine lining for implantation of an ovum; after implantation this steroid is necessary to maintain the endometrial lining of the uterus, stimulates mammary tissue growth for parturition, also synthesized in low levels in testes and adrenal cortex of both sexes

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8
Q

Cortisol

A

secreted by adrenal glands, in liver it acts to increase glycogen synthesis and gluconeogenesis, in skeletal muscle it acts to decrease both glucose uptake and protein synthesis, and increases protein catabolism, in adipose tissue it increases lipid mobilization and decreases glucose uptake (aka hydrocortisone)

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9
Q

Aldosterone

A

synthesized and released from adrenal cortex, increases reabsorption of Na+ at kidney, intestines, salivary glands, and sweat glands, increase in blood vol, BP, and blood flow

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10
Q

Testosterone

A

synthesized in male in Leydig cells of testes and aids in sperm maturation

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11
Q

Estradiol

A

primary estrogen in women, synthesized in theca cells of the ovarian follicles

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12
Q

Purines

A

Adenine (A) and Guanine (G)

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13
Q

Pyrimidines

A

Thymine (T) and Cytosine (C) and Uracil (U) in RNA

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14
Q

Phosphodiester Bond

A

links nucleotides together, backbone of DNA and RNA consists of alternating pentose and phosphates

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15
Q

What are the differences between DNA and RNA?

A

RNA uses uracil instead of thymine, ribose ring of RNA is hydroxylated at 2’ position whereas in DNA it’s not

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16
Q

messenger RNA (mRNA)

A

RNA polymers that allow for synthesis of proteins are called transcripts of mRNA

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17
Q

transfer RNA (tRNA)

A

RNA polymer that brings amino acids to site of protein synthesis

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18
Q

Chromatin

A

a complex of linear, double-stranded DNA, and protein (histones), as it prepares for division (mitosis and cytokinesis) the chromatin highly condenses into chromosomes

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19
Q

Gamete

A

egg or sperm, 23 chromosomes, (22 autosomes, 1 sex chromosome)

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20
Q

Zygote

A

fertilized egg, diploid or 2n, somatic cells, 23 pairs of chromosomes, 46 chromosomes total

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21
Q

How do chromatids becomes chromosomes?

A

individual chromatids become chromosomes when the centromere joining the sister chromatids divides and the chromatids are allowed to separate

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22
Q

Histones

A

basic proteins consisting of a high percentage of Lys and Arg

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23
Q

Nonhistones

A

proteins that associate with DNA, but are not histone proteins, they are acidic (-), e.g., RNA polymerase

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24
Q

Core Histones

A

H2A, H2B, H3, H4, bind roughly 1 and 3/4 turns of DNA or 146 base pairs

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25
Q

3 Major Phases of the Cell Cycle

A

Interphase (G1, S, and G2), Mitosis (prophase, metaphase, anaphase, telophase), Cytokinesis

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26
Q

First Growth Phase (G1)

A

G1 lasts about 10 hours, RNA and proteins are actively being synthesis

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27
Q

Synthetic Phase (S)

A

6-8 hours, each of the 46 strands of chromatin, except centromeres, are replicated

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28
Q

Second Growth Phase (G2)

A

2-6 hours, chromatin begins to condense becoming more tightly coiled, protein synthesis is active

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29
Q

Prophase

A

two centriole pairs move apart, microtubules begin to radiate from each pair in all directions, finishes with chromosomes, each with a pair of sister chromatids

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30
Q

Mitotic Spindle

A

formed by microtubules during prophase, these spindles separate chromosomes during anaphase

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31
Q

Metaphase

A

fully condense chromosomes align themselves along equator of cell (metaphase plate), nuclear membrane has complete disappeared

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32
Q

Anaphase

A

centromeres of each chromosome aligned on metaphase plate divide and two sister chromatids (now daughter chromosomes), move towards opposite poles (should have 92, 46 moving towards each pole)

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33
Q

Telophase

A

all daughter chromosomes have reached their respective poles, each chromosome uncoils/extends, microtubules of spindle apparatus disappear as nuclear membrane forms around each of 2 daughter nuclei, nucleolus reappears, cleavage furrow of cytokinesis deepens

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34
Q

Cytokinesis

A

cytoplasmic division of a cell into two daughter cells, begins during late anaphase and its completion signals the end of mitosis (or meiosis)

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35
Q

Meiosis

A

diploid 2N cells become haploid gametes (N), undergo DNA replication, then two nuclear divisions

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36
Q

Gametogenesis

A

formation of gametes

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37
Q

Reductive Division

A

after first nuclear division one cell with 46 chromosomes becomes two cells with 23 each, each will enter into interphase that precedes meiosis II

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38
Q

Meiosis I: Prophase I

A

long stage, further broken into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis

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39
Q

Leptotene

A

replicated chromosomes started condensing now becoming visible

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40
Q

Zygotene

A

homologous chromosomes begin to pair up longitudinally for crossing-over (genetic recombination aka synapsis)

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41
Q

Synaptonemal Complex

A

specialized protein and RNA scaffold, appears between the pairing chromosomes to join them

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42
Q

Pachytene

A

chromosomes continue to condense, become more distinct, genetic recombination occurs (crossing-over)

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43
Q

Diplotene

A

homologous chromosomes separate, crossing-over becomes visible at structures called chiasmata

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44
Q

Chiasmata

A

(singular: chiasma), at each chiasma any one of the four chromatids may be involved in a cross-over event

45
Q

Bivalent

A

refers to homologous chromosomes which have undergone synapsis

46
Q

Diakinesis

A

nuclear envelope begins to break down, nucleoli disappear, chiasmata move along lengths of chromatids until they reach ends, as homologous chromosomes begin to separate they appear to be joined to each other at their ends

47
Q

Metaphase I

A

homologous chromosomes align on metaphase plate, microtubules from spindle apparatus are attached at the centromeres and the nuclear membrane has disappeared

48
Q

Anaphase I

A

microtubules pull chromosomes apart, centromeres don’t divide, cytokinesis begins

49
Q

Telophase I

A

migrating chromosomes (dyads) complete movement to opposite poles, nuclear membrane reforms, cytokinesis more pronounced

50
Q

Cytokinesis

A

diploid cell with 46 chromosomes, divided into two haploid cells, each with 23 chromosomes

51
Q

Interphase II

A

second meiotic interphase is brief, DNA replication does not take place during S phase of interphase

52
Q

Meiosis II

A

quite similar to stages of mitosis

53
Q

Prophase II

A

chromosomes begin to condense, microtubules of spindle apparatus attach to the kinetochores of each chromosome

54
Q

Metaphase II

A

chromosomes line up along metaphase plate as haploid cells prepare for division

55
Q

Anaphase II

A

centromeres begin to divide, chromatids of each of 23 chromosomes are pulled to opposite poles of dividing cell, chromatids are no longer sister chromatids, DNA replication and crossing-over during pachytene of prophase I, DNA no longer the same

56
Q

Telophase II

A

a nuclear membrane forms around the expanding chromosomes, cleavage furrow deepens

57
Q

Cytokinesis (of Meiosis)

A

four haploid cells, each with 23 chromosomes, will have been derived from one diploid cell (each of the four cells enters interphase where they’re arrested at G1 phase)

58
Q

Sexual Reproduction

A

alternation of diploid and haploid phases of an organism’s life cycle

59
Q

Germ Cells

A

haploid, produced by meiosis

60
Q

Somatic Cells

A

diploid, produced by mitosis

61
Q

Micelles

A

spherical structures that are formed when enough phospholipids congregate together such that polar heads interact with water while the hydrophobic tails exclude water

62
Q

Lipid Bilayers

A

hydrocarbon tails of two phospholipid sheets interact with one another to exclude water

63
Q

Lateral Diffusion

A

allows neighboring phospholipids to easily exchange places

64
Q

Transverse Diffusion

A

movement of a phospholipid from one lipid plane to the next (a very rare event)

65
Q

Trans-membrane Proteins

A

span the lipid bilayer

66
Q

Simple Diffusion (passive)

A

movement of solute molecules through a lipid bilayer, from high conc. to low conc., down a concentration gradient

67
Q

Facilitated Diffusion

A

concentration gradient, but solute molecules must interact with integral membrane proteins embedded in the lipid bilayer

68
Q

Uniport

A

one type of solute molecule passes through a transmembrane protein in one direction

69
Q

Symport

A

two different types of solute molecules pass thru a membrane in the same direction

70
Q

Antiport

A

two different types of solute molecules pass thru a membrane in opposite directions

71
Q

Permeases

A

protein transporters that allow movement of a solute across a membrane

72
Q

Passive Transport

A

facilitated diffusion and simple diffusion

73
Q

Active Transport

A

solute is being transported against its concentration gradient, energy will be required

74
Q

Primary Active Transport

A

ATP powered, Na+-K+ pump is classic example

75
Q

Na+-K+ ATPase

A

maintain intracellular concentrations of Na+ and K+, antiport, two K+ ions into the cell for every three Na+ out

76
Q

Ca2+ ATPase

A

protein ensures that Ca2+ concentration within the cell is always at a low level by pumping two Ca2+ ions out of the cytosol for every ATP hydrolyzed

77
Q

Secondary Active Transport

A

ionic gradients made by primary active transport systems can provide a driving force that allows for the cotransport of other molecules against their concentration gradients

78
Q

Group Translocation

A

found in certain bacteria, sugar residue like glucose is phosphorylated as it is being transported through the plasma membrane

79
Q

Endocytosis

A

invagination of a portion of their membrane, will eventually pinch off to form an internalized vesicle (an endosome)

80
Q

Pinocytosis

A

cell drinking, invagination resulted in a vesicle containing liquid portion

81
Q

Phagocytosis

A

cell eating

82
Q

Bulk Transport

A

exocytosis and endocytosis

83
Q

Smooth Endoplasmic Reticulum

A

lacks ribosomes, appears more tubular in shape, involved in synthesis of a lot of cell’s membrane lipids, including neutral fats, phospholipids, prostaglandins, and steroid hormones

84
Q

SER of Hepatocytes

A

involved in hydroxylation reactions that aid in the detoxification of drugs

85
Q

Rough Endoplasmic Reticulum

A

ribosomes line face of it, bound to membrane by their large (60S) subunit, ribosomes synthesize membrane and secretory proteins that are then passed through the membrane of the RER and into the lumen post-translational modification begins, then proteins are shuttled to Golgi for more PTMs

86
Q

Golgi Apparatus

A

cisternae of Golgi is divided into three distinct regions, sorts and packages proteins on the trans face of the Golgi

87
Q

Cis Cisterna

A

face the nucleus and endoplasmic reticulum

88
Q

Trans Cisterna

A

face the plasma membrane

89
Q

Phosphatases

A

remove phosphate groups from sugar residues

90
Q

Peroxisomes

A

single membrane-bound organelles found within the cellular cytoplasm that contain a variety of enzymes

91
Q

Microfilaments

A

7 nm in diameter, made of G-actin—the monomers begin to polymerize and form a long, double-helical structure called F-actin, each G-actin monomer is arranged in the same direction giving polarity

92
Q

Cocci

A

spherical bacteria

93
Q

Spirilla

A

bacteria that have a rigid twist to their rod-like structure

94
Q

Prokaryotic cells

A

plasma membrane bounds cytoplasm, invaginations of bacterial cell membranes are called mesosomes, NO nucleus

95
Q

Does the cytoplasm of bacterial cells contain membrane-bound organelles?

A

No

96
Q

Inclusion Bodies

A

contain organic molecules like glycogen or inorganic stuff like phosphate granules

97
Q

Nucleoid

A

a region of prokaryotic cells that contains their circular, double-stranded DNA chromosome

98
Q

Plasmids

A

chromosomes which are circular and double stranded in bacteria

99
Q

Gram positive (+)

A

bacteria that stained purple, thick homogeneous peptidoglycan layer outside their plasma membrane

100
Q

Gram negative (-)

A

stain red or pink, much thinner peptidoglycan layer around plasma membrane, but around this layer is an outer membrane that contains lipopolysaccharides and porins to stabilize the membrane and act as an endotoxin

101
Q

Bacterial Conjugation

A

transfer of genetic info occurs by cell-cell contact (F+ = male, F- = female), F = fertility plasmid, F factor replicates by a process called rolling circle mechanism

102
Q

Transformation

A

uptake of genetic material from surrounding medium; this new genetic material is incorporated into host chromosome

103
Q

Transduction

A

transfer of bacterial genes by viruses

104
Q

Capsomers

A

building blocks composed of a specific number of individual proteins that make up the protein coat of viruses

105
Q

Viruses are made of:

A

a nucleic acid and a protein coat

106
Q

Naked Virus

A

gain access to host’s cytoplasm by receptor-mediated endocytosis—receptors are located near depressions called clathrin-coated pits

107
Q

Clathrin

A

acts as a scaffold that promotes vesicle formation on host cell

108
Q

Enveloped Viruses

A

enter host either through receptor-mediated endocytosis or by direct fusion with the plasma membrane

Berkeley MCAT Biology (9 decks)

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