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MCAT BIOLOGY FLASHCARDS > MCAT BIO CH. 5 PART 1 > Flashcards

MCAT BIO CH. 5 PART 1 Flashcards

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1
Q

What is a virus?

A

An obligate intracellular parasite

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2
Q

A vrirus can reproduce outside a cell. T/F

A

They are obligated to reproduce within (intra) a cell

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3
Q

What must occur for a virus to begin reproducing?

A

Commandeer the cellular machinery of the host and make copies of themselves

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4
Q

What is the definition of a virus to remember?

A

A virus is an obligate intracellular parasite that relies on host machinery whenever possible

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5
Q

Some viruses can store what?

A

ATP in their capsid

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6
Q

How is the viruses genome protected?

A

Nucleic acid genome packaged in a protein shell

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7
Q

A virus is inside its host cell. T/F

A

A virus is not inside a host cell, it contains only its genome

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8
Q

What type of nucleic acid do mature viruses have?

A

Does not contain nucleic acid other than its genome

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9
Q

What is a limiting factor of viral genomes? What size are viruses?

A

Size; small

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10
Q

What is a difficulty with the exterior protein shell of virus?

A

A rigid structure of fixed size that cannot expand to accommodate a larger genome

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11
Q

What is the likely result if a visa genome is tripled in size?

A

Viral genome will probably no longer fit within the normal viral structures

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12
Q

What is a bacteriophage?

A

Virus that infects bacteria

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13
Q

To adapt to size constraint, how has viruses adapted to?

A

Viral genomes have evolved to be extremely economical

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14
Q

What are the two adaptation for the viral genomes?

A
  1. Few genes

2. Encoding

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15
Q

What is the few genes adaptation fo viral genomes?

A

Viral genome to carry very few genes and for the virus to rely on host-encoded proteins for transcription, translation and replication

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16
Q

What is the encoding adaptation fo viral genomes?

A

Ability to encode more than one protein in a given length of genome

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17
Q

How can viral genomes encode more than one protein in a given length of genome?

A

Utilizing more than one reading frame within a piece of DNA so that genes may overlap with each other

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18
Q

What is capsid?

A

Protein coat surrounding the viral nucleic acid genome

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19
Q

What is used to classify viruses?

A

External morphology of the capsid

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20
Q

How is the capsid made?

A

From repeating patterns of only a few protein building blocks

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21
Q

How do helical capsid look? How do polyhedral capsids look like?

A

Helical capsids are rod-shaped

Polyhedral capsids are multiple-sided geometric

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22
Q

Which virus is commonly used in research and what is it?

A

T4 bacteriophage and its host is bacterium E. coli

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23
Q

What do tail fibers do for a virus?

A

Attach to the surface of the host cell

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24
Q

What do base plate do for a virus?

A

Attach to the surface of the host cell

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25
Q

What do sheath do for a virus?

A

Contracts using the energy of stored ATP and inject the genome into the host

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26
Q

The viral capsid is composed of….? The viral genome is composed of…?

A

proteins; nucleic acids

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27
Q

What do many animal viruses possess?

A

Envelope that surrounds the capsid

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28
Q

What is the envelope on animal viruses?

A

Membrane n the exterior of the virus derived from the membrane of the host cell

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29
Q

What does the envelope on animal viruses contain?

A

Phospholipids, proteins, carbohydrates, proteins encoded by the viral genome

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30
Q

What is budding based on animal viruses?

A

The process of acquiring envelope on the virus through the host cell membrane

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31
Q

How do some viruses leave their de-envelopped capsid inside the host cell?

A

By fusing their envelope with the host’s plasma membrane

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32
Q

What are naked viruses?

A

Viruses which do not have enveloppes

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33
Q

Which ones are naked viruses?

A

All phages and plant viruses

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34
Q

Why are phages and plant viruses are naked viruses?

A

Because they infect hosts with cell walls; when virus leaves the cell, the cell wall is destroyed and membrane ruptured

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35
Q

What is the first step in viral infection?

A

A virus binds to a specific receptor on the cell surface

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36
Q

What happens the virus binds to the cell surface receipt?

A

Virus all be internalized by either fusion or receptor-mediated endocytosis

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37
Q

Why might the antibodies to a viral capsid be ineffective in blocking infection?

A

It suggests that the virus is enveloped, so the antibody cannot reach its epitope on the capsid surface in infectious virus

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38
Q

From where do our immune system recognize for viruses?

A

The viral surface is also important for recognition by our immune system

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39
Q

Why can only specific species or specific cell types are susceptible to infection?

A

Only cells with a receptor that matches the virus will become infected

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40
Q

How do the viral genome produce energy and replicate?

A

Viral genome contains genes that redirect the infected cell to produce viral products

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41
Q

What is the first step to the bacteriophage life cycles?

A

Attachment or absorption

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42
Q

What is attachment or absorption based on bacteriophage life cycles?

A

Binding to the exterior of a bacterial cell in a process

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43
Q

What is the second step to the bacteriophage life cycles?

A

Penetration or eclipse

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44
Q

What is penetration or eclipse based on bacteriophage life cycles?

A

Injection of the viral genome into the host cell

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45
Q

Why is the second step to the bacteriophage life cycles also called eclipse?

A

Because the capsid remains on the outer surface of the bacterium while the genome disappears into the cell

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46
Q

After the penetration step, what two options can the phage follow?

A
  1. Lytic cycle

2. Lysogenic cycle

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47
Q

What happens as soon as the phage genome entered the host cell?

A

Host polymerases and/or ribosomes begin to rapidly transcribes and translate it

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48
Q

What is hydrolase?

A

A hydrolytic enzyme that degrades the entire host genome

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49
Q

Hydrolase is an example of what…?

A

An early gene

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50
Q

What is an early gene?

A

Genes that are expressed immediately after infection which includes any special enzymes required to express viral genes

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51
Q

How are multiple copies of the phage genome produced? What else is produced at the same time?

A

Using the dNTPs resulting from degradation of the host genome; abundance of capsid proteins

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52
Q

What do the capsid proteins do after an abundance of capsid proteins are made?

A

Each new capsid automatically assembles itself around a new genome

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53
Q

What enzyme is produced once each new capsid automatically assembled itself around a new genome?

A

Lysozyme

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54
Q

What is lysozyme an example of?

A

Late gene

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55
Q

What is the lysozyme?

A

Destroys bacterial cell wall

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56
Q

What happens when the lysozyme breaks the bacterial cell wall?

A

The host bacterium bust because osmosis is not counteracted by the protection of the cell wall

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57
Q

The lytic cycle is an efficient way to do what?

A

For a virus to rapidly increase its numbers

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58
Q

What is the problem with the lytic cycle?

A

All host cells are destroyed

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59
Q

What is a prophage?

A

Phage genome incorporated into the bacterial genome during lysogenic cycle

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60
Q

What is the host called after the prophage has occurred?

A

Lysogen

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61
Q

How is the prophage after it has occurred infiltrated the host genome?

A

Silent

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62
Q

Why is the prophage dormant?

A

Transcription of phage genes is blocked by a phage-encoded repressor protein

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63
Q

What does the phage-encoded repressor protein bind to?

A

Binds to specific DNA element in phage promoters

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64
Q

Every time the host cell reproduces itself in the lysogenic cycle….?

A

The prophage is reproduced too

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65
Q

What happens when the prophage becomes activated?

A

It removes itself from the host genome and enters the lytic cycle

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66
Q

What is excision?

A

The prophage removes itself from the host genome

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67
Q

Why is a downside from the lysogenic cycle?

A

When the viral genome activates, excising itself from he host genome may cause it to take part of the host genome along with it

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68
Q

What is transduction?

A

Codes for a trait that the new infected host did not previously possess

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69
Q

What is important about the tissue-specificity of animal viruses?

A

Due to the distribution of receptors necessary or absorption

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70
Q

Animal viruses enter the cells by what?

A

Endocytosis

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71
Q

What is endocytosis?

A

The host cell engulfs the virus and internalizes it

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72
Q

What happens once the animal virus is inside the hose?

A

Viral genome is uncoated

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73
Q

What does it mean when the animal virus is uncoated?

A

Its released from the capsid

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74
Q

If the animal virus doesn’t go through endocytosis, how does it get into the cell?

A

Fuse with the plasma membrane to release virus into the cytoplasm

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75
Q

What are the methods the animal virus can infiltrate the genome when its released into the cytoplasm?

A

Lytic cycle, productive cycle or lysogenic cycle

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76
Q

What is the productive cycle?

A

Similar to the lytic cycle but does not destroy the host cell

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77
Q

Why is the productive cycle possible?

A

The enveloped viruses exist the host cell by budding through the host’s cell membrane and becomes coated with the membrane in the process

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78
Q

How does budding not destroy the cell?

A

The lipid bilayer membrane can reseal as the virus leaves

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79
Q

What is provirus?

A

Analogous to a prophage, the dormant form of the viral genome

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80
Q

What does the + RNA Viruses must do?

A

Must encode RNA-dependent RNA polymerase and do not have to carry it

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81
Q

What is the structural component of + RNA virus?

A

A single stranded RNA genome

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82
Q

What is the simplest type of viral genome?

A

+ RNA virus

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83
Q

What is an + RNA virus?

A

A piece of single-stranded viral RNA which serves as mRNA

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84
Q

The viral genome acts directly as what, in the animal cell? (For + RNA virus)?

A

As mRNA

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85
Q

What does it mean when the genome is infective?

A

Injecting an isolated genome into the host cell with result in virus production

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86
Q

In order for the virus to replicate itself, one of the proteins it encode must be….?

A

An RNA-dependent RNA polymerase

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87
Q

What is the role of an RNA-dependent RNA polymerase protein?

A

To copy the RNA genome for viral replication

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88
Q

If a viral genome is (+) strand RNA, what is used as a template by the RNA-dependent RNA polymerase?

A

To make (+) strand copies of the genome, the virus needs the complementary strand as a template: (-) strand RNA

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89
Q

If the viral genome needs (-) strand, how does the dependent RNA poly do it?

A

Produces a (-) strand intermediate before generating new (+) strand genomes

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90
Q

What does the (-) RNA Viruses must do?

A

Must carry RNA-dependent RNA poly and encode it too

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91
Q

The genome of a (-) RNA virus is _____ to the piece of RNA that encodes viral proteins?

A

Complementary

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92
Q

What is the template for the viral mRNA production in (-) RNA virus?

A

The genome of a (-) RNA virus is the template for viral mRNA production

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93
Q

When the - RNA viruses enter the host cell, what happens?

A

Create a + strand from the - genome

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94
Q

What must the retroviruses do?

A

Encode reverse transcriptase

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95
Q

What is an important example of retrovirus?

A

HIV, AIDS and HTLV

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96
Q

What are retrovirus?

A

+ RNA viruses that undergo lysogeny

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97
Q

How do retrovirus integrate into the genome?

A

Integrate as proviruses

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98
Q

What must the retrovirus have in order to integrate DNA genome?

A

Must also be composed of double-stranded DNA

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99
Q

The retroviruses enter the cell as RNA, how can they be composed of double stranded DNA?

A

Must undergo reverse transcriptase to make an RNA template

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100
Q

How is reverse transcriptase accomplished?

A

By RNA-dependent DNA polymerase ended by the viral genome

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101
Q

Why is retroviruses not required to carry his enzyme?

A

The viral RA genome can be translated by host ribosomes; reverse transcriptase may be made after the viral genome

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102
Q

What are the three main retroviral genes?

A
  1. gag
  2. pol
  3. env
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103
Q

What is the gag retroviral genes?

A

Codes for viral capsid proteins

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104
Q

What is the pol retroviral genes?

A

Polymerase codes for reverse transcriptase

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105
Q

What is the env retroviral genes?

A

Envelope codes for viral envelope proteins

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106
Q

What does the Double-Stranded DNA Viruses must do?

A

Encode enzymes required for dNTP synthesis and DNA replication

107
Q

What must the double stranded DNA Viruses include?

A

Genes for enzymes involved in deoxyribonucleotide synthesis and DNA replication

108
Q

If retroviruses are added into the cellular genome and a reverse transcriptase inhibitor added to the cell; will the production of new viruses be blocked?

A

No; once the viral genome has integrated, transcription to produce viral mRNA and new viral RNA genomes does not involve reverse transcriptase

109
Q

Why doesn’t RNA viruses carry around genes for enzymes possessed by the host?

A

Transcription is always occurring in all cells, so NTPs are always present

110
Q

What is a factor likely to limit the size of RNA genomes?

A

The error rate in RNA synthesis is much higher than in DNA synthesis

111
Q

What are subviral particles? What are examples?

A

Infectious agents are smaller and simpler than viruses; prions and viroids

112
Q

How does prions don’t follow the Central Dogma?

A

Prions don’t have transcription and translation and have proteins being shaped based on other proteins (self-replicating)

113
Q

What happens when normally folded proteins comes into contact with the prion?

A

The prion acts as a template and the shape of the born protein is altered

114
Q

What are prions responsible for based on a class of diseases in mammals?

A

Transmissible spongiform encephalopathies (TSEs)

115
Q

What are the TSEs responsible for causing?

A

Cause degeneration in the nervous system; misfiled proteins found in the nervous tissues and resistant to degradation

116
Q

Wha is BSE referred to?

A

Mad cow disease

117
Q

What is a common disease that is apart of the TSEs?

A

Bovine spongiform encephalopathy (BSEs)

118
Q

What prion disease is similar to kuru?

A

Follows a similar transmission path in humans

119
Q

Where were kuru found and why?

A

Certain tribes that ate body parts (including brain) to honor the dead

120
Q

Prion disease are not genetically linked. T/F

A

False: genetically linked through mutations in the gene that codes for the prion protein

121
Q

Are prion disease common? How can they arise other than inherited?

A

No, they are rare; spontaneous

122
Q

How are prions characterized by?

A

By their very long incubation periods; leading to loss of coordination, dementia and death

123
Q

What are the physical structure of Viroids?

A

Short piece of circular, single-stranded RNA with extensive self-complementarity

124
Q

What is an ability of viroids?

A

Can base-pair with itself to create some regions hat are double-stranded

125
Q

What do viroids lack?

A

Do not code for proteins and lack capsids

126
Q

What are abilities of viroids?

A
  1. Catalytic ribozymes

2. Replicated, produce siRNAs that can silence normal gene expression

127
Q

What does replication of viroid shares similarity to?

A

To the replication of RNA viruses

128
Q

What does the viroid contain as enzyme to replicate?

A

RNA-dependent RNA polymerase

129
Q

What does the viroid RNA-dependent RNA polymerase do?

A

Synthesizes a (-) strand

130
Q

What is the (-) RNA strand circularized by, based on viroids?

A

RNA ligase

131
Q

What is RNA ligase derived by in viroids?

A

Derived from the host

132
Q

After the (-) is synthesized in viroid replication, what is it used for?

A

The round, rolling template to make more (+) copies that match the original RNA viroid sequence

133
Q

What is an other option for viroid replication other than synthesizing a (-) strand?

A

Leaves (-) strand in a more linear state where it can still act as a template for (+) strand creation and then become circularized

134
Q

What does the viroid do when the viroid hijack the cell’s DNA?

A

Viroids hijack the cell’s DNA dependent RNA polymerase and direct it to read RNA templates

135
Q

Most of the diseases caused by viroids are found where?

A

In plants

136
Q

What is the only human disease linked to viroids?

A

Is Hepatitis D

137
Q

How can Hepatitis D viroid can only enter ____ if it contained ____?

A

Hepatocytes (liver cells); contained in a capsid with a binding proteins

138
Q

What does successful Hepatitis D infection require?

A

Required confection with Hepatitis B from which it derives its capsid

139
Q

What is the cell theory?

A
  1. All living organisms are composed of 1 or more cells
  2. Cells are the monomer for any organism
  3. New cells arise from pre-existing, living cells
140
Q

The organism’s activity is determined by….?

A

The total activity of its cells

141
Q

What are basic biochemical processes prokaryotes and eukaryotes both are able to carry out?

A

Photosynthesis, the Krebs cycle and oxidative phosphorylation to produce ATP

142
Q

What is the primary feature of prokaryotes that distinguishes them from eukaryotes is what?

A

They do not contain membrane-bound organelles

143
Q

What does prokaryotes means?

A

Before the nucleus

144
Q

What groups do prokaryotes include?

A

Bacteria, archea and blue-green algae

145
Q

What is another word for archea?

A

Extremophiles

146
Q

What is another word for blue-green algae?

A

Cyanobacteria

147
Q

What is taxonomy used for?

A

Used to determinate evolutionary relationship of organisms to one another

148
Q

What is the largest taxonomic division?

A

Domain

149
Q

What are the three recognized domain?

A

Bacteria, Archea and Eukarya

150
Q

Which domains include prokaryotic organisms?

A

Domains, bacteria, and archea

151
Q

How can each domains be divided?

A

Subdivided into kingdoms

152
Q

What are the three well-recognized eukaryotic kingdoms?

A

Animalia, Plantae, and Fungi

153
Q

What are single-celled eukaryotes called?

A

Protist

154
Q

Which organelle is present in prokaryotic cells?

A

Ribosomes

155
Q

How is the prokaryotic genome?

A

A single double-stranded circular DNA chromosome

156
Q

Where is the prokaryotic genome not located?

A

Not in the nucleus

157
Q

The prokaryotic genome has histone proteins. T/F

A

False: not associated with histone proteins

158
Q

What are polyribosomes?

A

Many ribosomes translate a single piece of mRNA

159
Q

In prokaryotes, can transcription and translation occur at the same time?

A

Yes; they are in the same location

160
Q

What antibiotics are examples that interfere with bacterial translation without disruption human ribosome?

A

Streptomycin, tetracycline which bind only to bacterial ribosomes

161
Q

What are plasmids?

A

A circular piece of double-stranded DNA which is much smaller than the genome

162
Q

Which type of cells carry plasmids?

A

Prokaryotic cells

163
Q

How are plasmids usually called?

A

Extrachromosomal genetic elements

164
Q

What do the plasmids do?

A

Encode gene products

165
Q

What is an example of what plasmids usually carry?

A

Antibiotic-resistance genes

166
Q

What are antibiotic-resistance genes?

A

Genes that encode proteins which can break down antibiotics

167
Q

What are plasmids usually capable of doing?

A

Capable of autonomous replication

168
Q

What is autonomous replication is a plasmid?

A

A single plasmid molecule within bacterial cell may cause itself to be replicated into many copies

169
Q

What are plasmids important for?

A

Encoding advantageous gene products and conjugation

170
Q

What is conjugation?

A

Bacterial exchange of genetic information

171
Q

What are the three bacterial shapes?

A
  1. Round
  2. Rod-shaped
  3. Spiral-shaped
172
Q

What’s the proper name for round shape of bacterial shape?

A

Cocci

173
Q

What’s the proper name for rod-shape of bacterial shape?

A

Bacilli

174
Q

What’s the proper name for spiral-shaped of bacterial shape?

A

Spirochetes or spirilla

175
Q

How do animal cells deal with osmotic pressure due to their lack of cell wall?

A

By continuously pumping ions across the cell membrane

176
Q

Bacterial cells do not have a cell wall.

A

False: outside the lipid bilayer is a rigid cell wall

177
Q

What is the bacterial cell wall composed of?

A

Peptidoglycan

178
Q

What is peptidoglycan?

A

A complex polymer unique to prokaryotes

179
Q

What does peptidoglycan contain?

A

Contains cross-linked chains made of sugars and amino acids

180
Q

What amino acid does peptidoglycan contain and how do we know its a bacterial cell?

A

D-alanine, animal cells are L configuration

181
Q

Where is the lysozyme located based on animals? Made by what type of viruses?

A

In tears and saliva; made by lytic viruses

182
Q

How do peptidoglycan react to lysozyme?

A

Destroys the peptidoglycan in the bacterial cell wall,

183
Q

What’s the result of a destroyed peptidoglycan?

A

Protoplast

184
Q

What is the protoplast?

A

Osmotically fragile structure after peptidoglycan was destroyed

185
Q

What method is used to classify bacteria? What does it use to classify?

A

Gram staining; extent to which bacteria turn color

186
Q

What are the two gram staining groupings?

A
  1. Gram-positive

2. Gram-negative

187
Q

What is gram-positive bacteria?

A

Cell wall stain strongly; a dark purple colour

188
Q

What is gram-negative bacteria?

A

Stain weakly; a light pink color

189
Q

What do gram-positive bacteria contain, based on cell wall?

A

Thick peptidoglycan layer outside of the cell membrane; no other beyond this

190
Q

What do gram-negative bacteria contain, based on cell wall?

A

Thinner peptidoglycan layer in cell wall but have an additional outer layer containing lipopolysaccharides

191
Q

What is periplasmic space?

A

Intermediate space in gram-negative bacteria between the cell membrane and the outer layer

192
Q

What is usually found in periplasmic spaces?

A

Enzymes that degrade antibiotics

193
Q

What is the outer membrane of the gram-negative bacteria made of?

A

Endotoxins

194
Q

What can endotoxins affect in our body?

A

The immune system to have an extreme reaction and cause us to die

195
Q

When do endotoxins cause the most trouble?

A

When many bacteria die and their disintegrated outer membranes are released into the circulation

196
Q

What happens when many bacteria die and all their endotoxins go into circulation?

A

Immune system releases so many chemicals that the patient goes into septic shock

197
Q

What is septic shock?

A

Which much of the aqueous protein of the blood is leaked into the tissues, causing dropping blood pressure

198
Q

What type of chemical structure can endotoxins have?

A

Lipopolysaccharides, sugars bound to lipids

199
Q

Which type of bacteria release exotoxins? Are they toxic?

A

Gram + and -; very toxic

200
Q

How does the exotoxin help the bacterium?

A

Aid in compete again other bacterial species

201
Q

What is a capsule?

A

Sticky layer of polysaccharide surrounding the bacterial cell or entire colony of bacteria

202
Q

What’s another term for capsule?

A

Glycocalyx

203
Q

What does the capsule aid the bacteria with?

A

To adhere to smooth surfaces such as rocks in a stream or lining of the human respiratory tract

204
Q

What do the bacteria have for mobility?

A

Flagella

205
Q

What are flagella?

A

Long, whip-like filaments known as flagella

206
Q

Can viruses move via flagellar propulsion to find host cells?

A

No, they lack any means of energy production on their own

207
Q

When is a bacterium considered motile?

A

Possess one or more flagella because its teironly means of bacterial locomotions

208
Q

What does it mean for a bacteria to be monotrichous?

A

Flagellum located at only one end

209
Q

What does it mean for a bacteria to be amphitrichous?

A

Flagellum located at both ends

210
Q

What does it mean for a bacteria to be peritrichous?

A

They have multiple flagella

211
Q

What are the major components of the flagellum?

A

Filament, hook and the basal structure

212
Q

What is the structure of the basal structure?

A

Contains a number of rings that anchor the flagellum to the inner and outer membrane

213
Q

What does the basal structure serve?

A

Serve to rotate the rod and the rest of the flagellum

214
Q

What is the arrangement of the eukaryotic flagellum?

A

Contains a 9+2 arrangement of microtubules

215
Q

What is the rotation of the rod powered by?

A

The diffusion of the H+ down the portion gradient generated across the inner membrane by electron transport

216
Q

What is the process for the bacterial motion to be directed?

A

Chemotaxis

217
Q

The connection between chemotaxis and flagellar propulsion is dependent upon….?

A

Chemoreceptors

218
Q

Where are the chemoreceptors located and what do they do?

A

Chemoreceptors on the cell surface that bind attractants or repellents and transmit a signal to influence flagellar rotation

219
Q

The response of flagellar rotation is dependent on what, in bacterial cells?

A

A change in concentration over time

220
Q

What are pili?

A

Long projections on the bacterial surface involved in attaching to different surface

221
Q

What is the sex pilus?

A

Special pilus attaching F+ (male) and F- (female) bacteria

222
Q

What do sex pilus facilitate?

A

Facilitates the formation of conjugation bridges

223
Q

What are fimbriae?

A

Smaller structures involved in adhering to surfaces, not locomotion nor conjugation

224
Q

What are mesophiles?

A

Bacteria that favor mild temperatures; moderate temperature lovers

225
Q

What are thermophiles?

A

Heat lovers bacteria

226
Q

What are psychrophiles?

A

Cold lovers bacteria

227
Q

How might a decrease in temperature increase the bacterial growth?

A

Colds lovers possess enzymes that are optimally active at low temperatures

228
Q

Based on nutrition, how can bacterias be classified?

A

Their carbon source and their energy source

229
Q

What are autotrophs bacteria?

A

Utilize CO2 as their carbon source

230
Q

What are heterotrophs bacteria?

A

Rely on organic nutrients created by other organisms

231
Q

What are chemotrophs bacteria?

A

Get their energy fro chemicals

232
Q

What are phototrophs bacteria?

A

Get their energy from light

233
Q

What are four types of nutrition that bacterias have?

A
  1. Chemoautotrophs
  2. Chemoheterotrophs
  3. Photoautotrophs
  4. Photoheterotrophs
234
Q

What are chemoautotrophs?

A

Build organic macromolecules from CO2 using the energy of chemicals

235
Q

How do chemoautotrophs obtain their energy, what reaction do they go through?

A

By oxidizing inorganic molecules ex. H2S

236
Q

What are chemoheterotrophs?

A

Require organic molecules made by other organisms as their carbon source and for energy

237
Q

What are humans, based the four types of nutrition?

A

Chemoheterotrophs

238
Q

What are photoautotrophs?

A

Use only CO2 as a carbon source and obtain their energy from sun

239
Q

What are plants, based the four types of nutrition?

A

Photoautotrophs

240
Q

What are photoheterotrophs?

A

Get their energy from the sun but require an organic molecule made by another organism as carbon source

241
Q

What media do bacteria usually grow in?

A

Agar

242
Q

What is a plaque based on bacterial growth media?

A

A clear area in the lawn

243
Q

What is a lawn based on bacterial growth media?

A

Dense growth of bacteria

244
Q

How do plaques happen, based on growth media?

A

Result from death of bacteria and are caused by lytic viruses or toxins

245
Q

What is minimal media?

A

Contains only glucose and agar

246
Q

What is doubling time?

A

Amount of time required for a population of bacteria to double its number

247
Q

What are auxotroph bacteria?

A

Bacterium which cannot survive on minimal medium because it can’t synthesize a molecule it needs to live

248
Q

What do auxotroph bacteria need to grow?

A

Auxiliary trophic substances; substances added to survive

249
Q

How do auxotrophy occur?

A

Mutation in a gene coding for an enzyme in a synthetic pathway

250
Q

How would you denote a bacteria that can metabolize saccharide lactose? What about one that cannot?

A

lac+, lac-

251
Q

What are obligate aerobes?

A

Bacteria which require oxygen

252
Q

What are anaerobes?

A

Bacteria that do not require oxygen

253
Q

What are the three subcategories in anaerobe metabolism?

A
  1. Facultative anaerobes
  2. Tolerant anaerobes
  3. Obligate anaerobes
254
Q

What are facultative anaerobes?

A

Will use oxygen when around but don’t need it

255
Q

What are tolerant anaerobes?

A

Can grow in absence or presence of oxygen but don’t use for metabolism

256
Q

What are obligate anaerobes?

A

Poisoned by oxygen

257
Q

Why can obligate anaerobes be poisoned by oxygen?

A

Lack certain enzymes necessary for the detoxification of free radicals which form when O2 is around

258
Q

What is a harmful O2 by product?

A

O2^-

259
Q

What is respiration?

A

Glucose catabolism with use of an inorganic electron acceptor such as oxygen

260
Q

What is fermentation?

A

Glucose catabolism which uses a reduced by-product of glucose catabolism

261
Q

What type of reduced by-product of glucose catabolism can be used by fermentation?

A

Lactate or ethanol

262
Q

What is anaerobic respiration?

A

Glucose metabolism with electron transports and oxidative phosphorylation relying on an external electron acceptor OTHER than O2

263
Q

Where are the electrons passed to in fermentation?

A

From NADH to pyruvic acid

264
Q

What is a possible electron acceptor based on anaerobic respiration?

A

NO3^-

MCAT BIOLOGY FLASHCARDS (23 decks)

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