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biology 1 Flashcards

1
Q

Where is DNA held?

A

nucleus

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2
Q

A small amount of nuclear DNA is found in the __

A

mitochondria

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3
Q

What is the nucleolus?

A

the site of rRNA transcription and ribosome assembly

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4
Q

Where are proteins that are bound to the ER, golgi, lysosomes, endosomes, plasma membrane or secreted outside the cell made?

A

the RER

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5
Q

Where are proteins that remain in the cytosol made?

A

free floating ribosomes

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6
Q

Where in the cell are lipids synthesized?

A

smooth ER

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7
Q

Where are lipids metabolized?

A

in the mitochondria

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8
Q

What is the function of the golgi apparatus?

A

organize and distribute proteins, continue post translational modification

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9
Q

How are mitochondrial genes passed down?

A

maternal side

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10
Q

What is the endosymbiotic theory?

A

suggests mitochondria evolved from aerobic prokaryotes that were engulfed by a larger host.

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11
Q

Where is the pH higher, the matrix or the inter membrane space of the mitochondria?

A

matrix has higher pH (protons are pumped into intermembrane space)

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12
Q

What would happen if hydrogen ion channels were placed in the mito mem?

A

less ATP production because there would be an alternate route from ATP synthase

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13
Q

What is thermogenin?

A

protein channel in the inner membrane of mito that allows the passage of protons (brown fat)

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14
Q

What are the main functions of centrioles/centrosomes?

A

centrosome - organizes microtubules, flagella, and cilia (plays key role in cell division)

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15
Q

What is the pH of a lysosome? What is its function?

A

5, digest cell parts, fuse with phagocytic vesicles, participate in apoptosis

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16
Q

What is the function of peroxisomes?

A

self-replicate, detoxify chemicals, participate in lipid metabolism

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17
Q

What is tubulin?

A

a globular protein that polymerizes to form microtubules

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18
Q

What are microtubules?

A

make up the cytoskeleton, 2 types of tubulin: alpha -tubulin, beta-tubulin
protofilmament- heterodimer

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19
Q

How many protofilaments in a microtubule?

A

13

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20
Q

What is the cytoskeleton?

A

scaffolding-like network of microfilaments, microtubules, and intermediate filaments that provides structure to the cell

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21
Q

What is the spindle apparatus?

A

array of microtubules that grows outwards from the centrioles during mitosis to bind with the centromere of the chromosomes at the metaphase plate

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22
Q

What is actin?

A

protein monomer that polymerizes to form microfilaments

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23
Q

What is an intermediate filament?

A

general class of several proteins that polymerize to form filaments that are intermediate in diameter.

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24
Q

What is myosin?

A

motor protein (9+2) arrangement found in eukaryotic cilia and flagella

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25
Q

What is the difference between flagella and cilia?

A

flagella - used for locomotion (sperm)

cilia - beating pattern - moves fluids and other substances past the cell

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26
Q

In humans, where is cilia found?

A
  • respiratory system (lungs)
  • nervous system (ependymal cells)
  • reproductive system (uterine tubes)
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27
Q

What problems would a disease that prevented microtubule production cause?

A

weakened cytoskeletons, would not be able to complete mitosis or meiosis, ciliated epithelial cells would lose their function

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28
Q

What is the difference between the movement of eukaryotic and prokaryotic flagella?

A

eukaryotic- whipping motion - microtubules made of tubulin

prokaryotic - spinning/rotating motion- simple helices made of flagellin

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29
Q

describe the fluid mosaic of the phospholipid bilayer

A

phospholipids are mobile and can exchange positions with each other and move laterally across the leaflets

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30
Q

What is the difference between simple and facilitated diffusion?

A

simple- NO ATP required (relies on concentration gradient)

facilitated - NO ATP required (needs proteins in the membrane)

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31
Q

What is the difference between a hypertonic, hypotonic, and isotonic solution?

A

hyper- more solute
hypo- less solute
iso- no net flow of water in either direction

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32
Q

What characterizes active transport?

A

required when something is moved against its concentration gradient or against an electrical potential

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33
Q

What is secondary active tranport?

A

no direct coupling of ATP required

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34
Q

what are tight junctions, gap junctions, and adherens junctions?

A

tight - water-proof barriers
gap- tunnels between adjacent cells allowing exchange
adherens - strong mechanical attachments

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35
Q

What is the strongest type of cellular junctions?

A

desmosomes

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36
Q

Where are tight junctions found in the body?

A

epidermis of the skin

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37
Q

Where are gap junctions found in the body?

A

junctions between cardiac muscle or smooth muscle

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38
Q

Where are adherens junctions found in the body?

A

epithelium and between cardiac muscle cells

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39
Q

Where are desmosomes found in the body?

A

epidermis (stratified epithelium)

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40
Q

What type of tissue is blood? adipose tissue?

A

both connective tissue

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41
Q

describe the G-protein cascade

A
  1. signal molecule binds to an IMP (GPCR)
  2. causes conformational change that activates the cytosolic domain
  3. G protein (alpha subunit binds both GTP and GDP), signal causes GTP to substitute GDP, activating the alpha subunit and separates from beta and gamma subunits
  4. g protein is agonist for adenylyl cyclase - makes cAMP from ATP
  5. cAMP is agonist for PKA, which phosphorylates proteins
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42
Q

What is a paracrine signal?

A

signal molecules secreted by one cell bind to receptors on other cells in a local area (NT in synapse)

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43
Q

What is autocrine signaling?

A

signal secreted by cell bind to receptors on the same cell

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44
Q

What is intracrine signaling ?

A

signal molecules (usually steroids) bind to receptors inside the same cell that produced them, without being secreted outside.

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45
Q

What is juxtacrine signaling?

A

signaling requires direct contact between two cells

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46
Q

Describe the cell cycle. What is G0 phase?

A

G1 (growth)- S (synthesis)- G2 (growth, high metabolic activity) - M (mitosis)

G0- not actively dividing (differentiated cells)

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47
Q

What is a histone?

A

proteins around which the DNA helix is wrapped during the first step of DNA condensation

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48
Q

What is a nucleosome?

A

set of 8 histone proteins in a cube shape with DNA coiled around it

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49
Q

What are homologues and sister chromatids?

A

homologues - two related but non-identical chromosomes

sister chromatids - identical

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50
Q

What is the difference between the kinetochore and the centromere?

A

centromere- region of the chromosome that joins the sister chromatids
kinetochore - group of proteins where spindle fibers attach to during mitosis and meiosis

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51
Q

When does crossing over occur?

A

prophase 1

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52
Q

What is nondisjunction and when can it occur?

A

chromosomes fail to separate properly during anaphase during meiosis 1, meiosis 2, or mitosis

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53
Q

What are the 3 components of the nucleotide?

A

phosphate backbone, sugar and nitrogenous base

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54
Q

What other biomolecules, besides RNA and DNA, are nucleotides?

A

cAMP, NADH, FADH2, FMN, coenzyme A, ATP, GTP, UTP

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55
Q

How many hydrogen bonds between AT?

How many hydrogen bonds between GC?

A

2 AT

3 GC

56
Q

What does semi-conservative replication mean?

A

each newly formed daughter helices consists of one original strand paired with one newly-replicated strand

57
Q

What does semi-discontinuous replication mean?

A

one strand is synthesized continuously and the other strand is synthesized in Okazaki fragments

58
Q

What does the enzyme RNase H do in DNA replication?

A

removes RNA primers

59
Q

In DNA replication, what direction is DNA read and what direction is it replicated?

A

read- 3’- 5’

made - 5’ -3’

60
Q

Why does the newly replicated strand of DNA become shorter than the parent strand?

A

5’ end of DNA does not have existing free 3’ hydroxyl so DNA polymerase cannot replace that section of primer

61
Q

What is the enzyme that adds length to telomeres?

A

telomerase

62
Q

What are the 3 causes of DNA damage?

A

spontaneous hydrolysis, damage by external chemicals or radiation, mismatched base pairs

63
Q

What causes mismatched base pairs in DNA?

A

errors during replication or methylation of guanine

64
Q

How do chemicals or radiation impact DNA?

A

radiation - neighboring pyrimidines react to form covalent dimers
carcinogens- bind to DNA (bulky side groups)

65
Q

What are the 4 mechanisms of DNA repair?

A

proofreading - DNA polymerase catches and repairs most mismatched pairs

mismatch repair system- enzymes that scan newly copied DNA, and locate, excise and replace mismatched pairs

base excision- base only excised first via DNA glycosylase , other enzymes remove sugar-phosphate backbone, then DNA polymerase and ligase replace nucleotide

Nucleotide excision - excision of an oligonucleotide that includes several bases on either side of the error

66
Q

Explain the steps of PCR

A
  1. DNA heated to 95 celcius to unwind
  2. primers are added (2- one for 3’ of sense one for 3’ antisense) cooled down to (50-65 celcius)
  3. temp raised to 72 celcius for taq polymerase to polymerize DNA
  4. repeat cycle
67
Q

What piece of information must be known in order to perform PCR?

A

the exact DNA squence

68
Q

What is a southern blot used for?

A

used to verify the presence/absence of specific DNA sequence and indicate size of restriction fragments

69
Q

what is the northern blot used for?

A

nearly identical of southern blot, used on RNA instead of DNA

70
Q

What is the western blot used for?

A

used on protein segments instead of nucleotides. the probes are radiolabeled antibodies rather than nucleotide sequences

71
Q

What is an eastern blot used for?

A

similar to western blot, but used to verify post-translational modification. the probes used bind to lipids, carbs and phosphates

72
Q

What are the differences between DNA and RNA?

A

RNA- 2’ OH group, single stranded, uracil, exits nucleus into the cytoplasm
DNA - always stays in the nucleus, thymine, double stranded

73
Q

What is the function of rRNA?

A

rRNA- polymer of which ribosomes are made, ribosomes are assembled in the nucleolus

74
Q

What is the function of tRNA?

A

has anti-codon and covalently bonded amino acid on one end. Assists in translation of proteins

75
Q

What is the function of mRNA?

A

complementary RNA strand copied from DNA template strand.

76
Q

What is alternate splicing?

A

after introns are removed from mRNA transcript, the exons can be assembled in a number of different orders, each results to a different protein

77
Q

What are other terms for template strand?

A

anti-coding, anti-sense

78
Q

The Lac operon codes for__

A

translation of lactase

79
Q

Will the lactase gene be transcribed in the presence of glucose but no lactose?

A

no, inhibitor is bound

80
Q

Will the lactase gene transcribed in the presence of lactose and no glucose?

A

yes

81
Q

Will the lactase gene transcribed in the presence of no glucose or lactose?

A

no

82
Q

Will the lactase gene transcribed in the presence of lactose and glucose?

A

no, inhibitor would not be bound, but cAMP levels (activator) will be low when glucose is present

83
Q

What 3 mechanisms are genes regulated by?

A

rate of transcription- RNA has short half life, gene only expressed if DNA is continuously transcribed

activators or repressors- regulatory molecules up regulate transcription (hormones, lactose, glucose)

permanent or semi-permanent suppression - methylation or other covalent modification

84
Q

What are the 3 stop codons?

A

UGA, UAG, UAA

85
Q

What does it mean when the human genetic code is described as degenerative and unambiguous?

A

degenerative- redundant (multiple codons can code for same aa)
unambiguous - the aa is known by the codon

86
Q

What are the 3 sites of the ribosome in translation?

A

aminoacyl, peptidyl, exit site

APE

87
Q

In translation, which direction does the ribosome read the mRNA?

A

5’ to 3’

88
Q

What is the enzyme that charges the tRNA during translation?

A

aminoacyl-tRNA synthetase

89
Q

Where does translation occur?

A

cytoplasm

90
Q

Where does post-translation modification occur?

A

ER and golgi apparatus

91
Q

What is a mutation?

A

any change in the DNA sequence

92
Q

what is a point mutation?

A

single base pair substitution

93
Q

What is a missense mutation?

A

changes the codon so that a different amino acid will be incorporated

94
Q

What is a silent mutation?

A

does NOT alter amino acid sequence

95
Q

What is a frameshift mutation?

A

changes the reading frame

96
Q

What is a neutral mutation?

A

does not negatively impact the fitness of the individual

97
Q

What is a nonsense mutation?

A

changes normal codon to a premature stop codon

98
Q

What is a proto-oncogene?

A

normal genes that regulate cell division, cell cycle, growth, apoptosis

99
Q

What are tumor suppressor genes?

A

help protect the cell from uncontrolled growth, they require 2 recessive alleles to lose function

100
Q

What is the mendelian ratio ?

A

3: 1 phenotypic ratio
1: 2:1 genotypic ratio

101
Q

What is a test cross?

A

cross between a homozygous recessive and an individual with at least one dominant allele

102
Q

What is the law of segregation?

A

Alleles segregate independently of one another when forming gametes

103
Q

What is the law of independent assortment?

A

Genes located on different chromosomes assort independently

104
Q

If a genetic problem has BOTH or AND

A

multiply probabilities together

105
Q

If a genetic problem has EITHER (OR) how do you solve?

A

add probabilities together

106
Q

What is incomplete dominance?

A

phenotypes of the dominant and recessive alleles appear to be mixed or blended in the phenotype of a heterozygote. (roses)

107
Q

What is genetic co-dominance?

A

both phenotypes are expressed fully at the same in a heterozygote (blood antigens)

108
Q

What is incomplete penetrance in genetics?

A

occurs when various individuals all have identical genotypes and yet some have the disease phenotype and others don’t

109
Q

What is limited expressivity in genetics?

A

various individuals all have the same genotype AND all have the disease phenotype but they are impacted by varying degrees

110
Q

What does polygenic mean?

A

many genes contribute to one trait

111
Q

What is pleiotropy?

A

one single gene contributes to multiple traits

112
Q

What is mosaicism?

A

different cells within the same individual contain non-identical genotypes

113
Q

What does epigenetic mean?

A

heritable phenotype resulting from any process other than a change in DNA itself

114
Q

What is genetic imprinting?

A

when one specific gene is expressed differently depending on which parent it originated from

115
Q

In order for natural selection to occur:

A
  1. One individual must have a polymorphism that provides an evolutionary fitness advantage
    2) That advantage must result in the individual with the favored polymorphism differentially producing more offspring.
116
Q

What is a gene pool?

A

complete set of genes and alleles in a population

117
Q

What is adaptive radiation?

A

rapid formation of a variety of species from one ancestral species - usually characterized by a strong environment -species connection

118
Q

What is evolutionary bottleneck?

A

sudden decrease in the number of individuals in a population

119
Q

What is genetic drift?

A

change in the allele frequency within a population due to random, non-genetic, non-selective factors

120
Q

What is convergent evolution?

A

when two species arrive at a point where they have similar functional forms, but they have developed those similar forms via evolutionary pathways

121
Q

What is divergent evolution?

A

species develop different forms AND form new species, all radiating from same common ancestor

122
Q

What are the 5 Hardy Weinberg assumptions?

A

1) Large population
2) No mutation
3) No immigration or emigration
4) Random mating
5) No natural selection

123
Q

What are the Hardy Weinberg equations?

A

p2 + 2pq + q2 = 1
p+ q= 1

p2- fraction of individuals who have TT
q2- fraction of individuals who have tt
2pq- Tt

124
Q

What is the order of classification starting from kingdom?

A

Kingdom, Phylum, Class, Order, Family, Genus, Species

125
Q

What is phylogeny?

A

a shared evolutionary history can reveal similarities

126
Q

All fungi are ____

A

heterotrophs

127
Q

fungi have cell ___ made of __

A

walls; chitin

128
Q

how do yeasts reproduce?

A

budding

129
Q

What is mutualism?

A

a form of symbiosis where both participants benefit equally

130
Q

What is commensalism?

A

symbiosis in which one participant benefits and the other participants experience is neutral

131
Q

What is parasitism?

A

a symbiosis where one participant benefits at the expense of the other

132
Q

What is a lichen?

A

symbiosis between fungi and algae

133
Q

What is mycorrhizae?

A

symbiosis between fungi and plant roots

134
Q

What are the structural differences between HIV and a bacteriophage?

A

HIV- small spherical enveloped virus, reverse transcriptase, RNA
bacteriophage- capsid head, tail, tail fibers

135
Q

Difference between lytic and lysogenic cycle

A

lytic - viral genes are actively transcribed and new viruses are assembled

lysogenic - dormant cycle, viral DNA is incorporated

136
Q

What are the 3 ways bacteria reproduce?

A

conjugation- One bacteria must have an F plasmid (F+); the F plasmid is a plasmid containing the gene for a sex pilus. The recipient can be (F-)

Transformation: Bacteria pick up DNA from the environment.

Transduction: Viruses accidentally incorporate host genetic material into their nucleic acids.

137
Q

Difference between gram positive and gram negative

A 
Gram pos- 
- Stain purple
• Very thick cell wall
• Form endospores
• Single cell membrane
gram neg- 
• Stain pink
• Relatively thin cell wall
• Do NOT form endospores
• Contain two (2) cell membranes: one inside the cell wall and one outside the cell wall.

mcat (15 decks)

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