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Biology Test 2 > Test 3 > Flashcards

Test 3 Flashcards

1
Q

What are the 5 main functions of cell membrane?

A

1) Boundary and permeability barrier
2) organization and localization of function
3) Transport processes
4) signal detection
5) cell to cell communication

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2
Q

What is the function of boundary and permeability barrier?

A

To keep desirable things IN and undesirable things OUT

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3
Q

What prevents polar or charged molecules from crossing the membrane without help?

A

Hydrophobic interior

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4
Q

What is the membrane made of?

A

phospholipid bilayer with the tails pointing inside

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5
Q

What is the function of Organization and localization?

A

intracellular membranes compartmentalize various functions within organelles
-each organelle has particular proteins associated with its membrane that have specific functions

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6
Q

What is the function of Transport Process?

A

proteins found in each membrane can selectively transport solutes across the membrane
-selectively designed for what is suppose to come in and out

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7
Q

What is the function of signal detecting?

A

proteins found in the cell membrane detect electrical and chemical signals from outside the cell

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8
Q

What happens in cancer that pertains to signal detecting?

A

cells grow out of control and only happens if signaling pathways are messed up in which they stay on the entire time

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9
Q

What is the function of cell adhesion and communication?

A

Tight Junctions, Gap Junctions, Adhesive Junctions, membranes are made of proteins

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10
Q

What is more than half of the membrane composed of?

A

Protein

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11
Q

What is less than half of the membrane composed of?

A

Lipids

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12
Q

What are the three main classes of membrane lipids?

A

Phospholipids
Glycolipids
Cholesterol

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13
Q

What is Tay-Sachs disease?

A

body can’t break down gangliosides= accumulate in brain and nerves= impaired function, paralysis, severe mental deterioration, death

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14
Q

What does not contain cholesterol?

A

prokaryotes or mitochondria

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15
Q

True or False. Lipids are distributed equally in a membrane?

A

False, Glycolipids are exclusively in outer layer while PE, PI, PS are more prominent in the inner layer

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16
Q

Why can’t lipids flip flop?

A

due to the hydrophilic and hydrophobic layers. The hydrophilic head won’t go through hydrophobic areas

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17
Q

What are the 3 Movements/ explain that phospholipid molecules can do within membranes

A 
Rotation (rotate in same spot)
Lateral Diffusion (Moves within same layer)
Transverse diffusion "flip-flop" ( lipid moves from one layer to other, but this can't be done on its own)
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18
Q

What lipid can be as high as 50% in the membrane?

A

cholesterol

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19
Q

The rigid structure of cholesterol causes membranes to what at higher temperatures?

A

Less fluid

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20
Q

Cholesterol also keeps fatty acid chains from packing how?

A

too tight

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21
Q

At lower temperatures, the structure of cholesterol gives the membrane what?

A

more fluid

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22
Q

Less cholesterol will pack between lipids in higher temperatures why?

A

because lipids will expand

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23
Q

More cholesterol will pack between lipids in lower temperatures why?

A

When lipids, which are packed tight, need more expansion

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24
Q

What does cholesterol reduce?

A

permeability of membranes to small molecules

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25
Q

What type of bond forms between phospholipid and cholesterol in membrane?

A

hydrogen bonds

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26
Q

What are lipid rafts?

A

areas in a membrane that are thicker and less fluid than the rest of the membrane

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27
Q

What are lipid rafts high in?

A

cholesterol, glycolipids and saturated fatty acids

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28
Q

Why do unsaturated fatty acids have more fluid?

A

because they are bent and allow for more space and more fluid. The saturated fats are straight and pack tighter together with less fluid

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29
Q

What molecules are easily permeable through membrane?

A

Hydrophobic molecules (O2, CO2, N2, benzene)

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30
Q

What molecules can get across as long as they are not charged?

A

H2O, urea, glycerol

charged molecules can’t get through hydrophobic interior

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31
Q

What is able to get across the membrane sometimes?

A

large uncharged polar molecules, glucose, sucrose

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32
Q

What is not able to get through the membrane unless with help?

A

Ions, H+, Na+, HCO3-, K+, Ca2+, Cl-, Mg2+

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33
Q

What types of molecules NEED to get in and out of membrane bound organelles?

A

Water, Oxygen/CO2, Sugars, Amino Acids, Ions, ATP

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34
Q

What are the holes in nucleus called/ what is the structure?

A

Nuclear pores that are filled with proteins and are highly regulated and controlled

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35
Q

How does a cell get molecules that are water-soluble (hydrophilic) ACROSS a membrane?

A

various proteins

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36
Q

What are the four protein processes?

A

Simple diffusion
Facilitated diffusion (carrier proteins)
Active transport
Facilitated diffusion (channel proteins)

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37
Q

What is Simple diffusion?

A

when molecules are small enough and uncharged and are able to cross without help

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38
Q

What is Facilitated diffusion through a carrier protein?

A

Carrier protein binds and carries the molecule and then releases

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39
Q

Does facilitated diffusion require energy?

A

If it is going with the gradient, then no. If going against, yes

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40
Q

What is Facilitated diffusion through a channel protein?

A

like pores that are very selective and specific to what can get across

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41
Q

What is Active transport?

A

Requires ATP, pump that pumps molecules across

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42
Q

What is the definition of simple diffusion?

A

Unassisted movement of a molecule from an area of HIGH concentration to an area of LOW concentration
Only works for small, nonpolar molecules (like gases)

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43
Q

Diffusion is movement towards what?

A

an equilibrium

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44
Q

What is hypertonic?

A

high solute concentration

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45
Q

What is hypotonic?

A

Low solute concentration

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46
Q

What is osmosis?

A

movement of water from hypotonic to hypertonic solution

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47
Q

What are the 2 types of proteins involved in transport?

A

carrier and channels

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48
Q

What are the two types of transport?

A

passive and active

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49
Q

What is passive transport?

A

solute is moving with the gradient. (high to low)

no energy is required

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50
Q

What is active transport?

A

solute is moving against the gradient (low to high)

requires energy

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51
Q

Carrier proteins are often called what?

A

transporters or permeases

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52
Q

What is the mechanism of carrier proteins?

A

1) Bind
2) conformational change
3) release molecule(s)
4) return to original conformation

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53
Q

What is symport?

A

when molecules flow through the same direction

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54
Q

What is antiport?

A

When molecules flow through in opposite directions

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55
Q

Do channel proteins undergo a conformation change upon binding a solute?

A

No, they simply form a channel

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56
Q

What is the channel proteins lined with?

A

hydrophilic amino acids

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57
Q

What is the size of channel proteins?

A

typically the size of the molecules

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58
Q

How fast do channel proteins pass molecules?

A

1,000,000 ions/second

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59
Q

How are channel proteins very selective?

A

only allow 1 type of ion to pass through

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60
Q

What is endergonic in nature?

A

active transport

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61
Q

What is active transport?

A

against the gradient “UPHILL”

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62
Q

What are active transport proteins often called?

A

pumps

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63
Q

Active transport can be what two things?

A

direct or indirect

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64
Q

What is direct active transport?

A

transport is coupled directly to ATP hydrolysis energy is used to drive pump

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65
Q

What is Indirect active transport?

A

transport of 1 molecule uphill is coupled with the transport of 1 molecule downhill (pulley system)

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66
Q

How do differences in ACTG account for observable and behavioral differences?

A

These bases code for different proteins that are made unique to each other and these proteins are what distinguish our features and do functions

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67
Q

DNA contains what which provides the info to make proteins?

A

genes

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68
Q

What is the cell cycle of mitosis?

A

1) DNA replication

2) Cell division

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69
Q

What is the structure of DNA

A

Nucleic acid structure that is in double helix formation

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70
Q

What is the nucleic structure of DNA made up of? (What are the individual parts)

A

nucleotides

71
Q

What acts as the intermediate part between DNA and proteins?

A

RNA

72
Q

What is a codon?

A

every three nucleotide bases that codes for 1 amino acid

73
Q

What are the 4 nucleotide bases of DNA

A

CGAT

74
Q

On DNA, how do the strands run?

A

antiparallel
3’ to 5’
5’ to 3’

75
Q

What type of bond forms between nucleotide bases in DNA that give DNA its structure?

A

hydrogen bonds

76
Q

The A nucleotide base pairs with what nucleotide base?

A

T unless in mRNA then its U

77
Q

The C nucleotide base pairs with what nucleotide base?

A

G

78
Q

What makes up a nucleotide? (3 parts)

A

phosphate, sugar, base

79
Q

G and C are bonded with how many hydrogen bonds?

A

3

80
Q

A and T are bonded with how many hydrogen bonds?

A

2

81
Q

What is a Genome?

A

one complete copy of all the DNA in a cell

82
Q

What is the size of the human genome (approx bases)

A

3 billion

83
Q

In general as the organism is more complex, what else is more complex?

A

genome

84
Q

How is DNA packaged in the cell? (what is the unit)

A

chromosome

85
Q

How many chromosomes does a human have?

A

23 pairs

86
Q

How many meters of DNA do humans have

A

2 meters

87
Q

What forms the beads on a string look for DNA

A

complexes and groups with DNA wound around

88
Q

What size group do histones come in?

A

groups of 8

89
Q

How are chromosomes organized and numbered?

A

In length

90
Q

Where are chromosomes found?

A

In nucleus

91
Q

Where does rRNA come together with subunits before leaving the nucleus?

A

nucleolus

92
Q

What is rRNA

A

ribosomal RNA which is a protein and RNA

93
Q

What place in the cell is considered the ribosome factories?

A

nucleolus

94
Q

Other than the nucleus, what other organelle has its own DNA?

A

mitochondria (tRNA and genes for complexes found/ used in mitochondria)

95
Q

How many genes approximately in humans?

A

20,000

96
Q

A gene codes for what?

A

1 protein

97
Q

Where does transcription take place?

A

nucleus

98
Q

Where does translation occur?

A

In cytoplasm

99
Q

What is transcription?

A

copying gene in form of RNA to be transported out of nucleus into cytoplasm that can be translated into protein

100
Q

What unit of DNA is small enough to leave nucleus?

A

mRNA

101
Q

What sugar does DNA contain?

A

deoxyribose sugar

102
Q

What sugar does RNA contain?

A

ribose sugar

103
Q

What is the difference and on which carbon is the difference for RNA and DNA?

A

hydroxyl group on RNA on carbon 2

104
Q

For bases, DNA has thymine while RNA has…

A

uracil

105
Q

Difference in structure of DNA and RNA?

A

DNA is usually double stranded while RNA is single stranded

106
Q

What is DNA made of?

A

nucleotides with 4 different bases

107
Q

mRNA is typically what structure of molecule?

A

linear, with no branches and folds into a shape but is synthesized as straight linear molecule

108
Q

If there is a mutation, which base number will it usualy occur at?

A

Base 3 as most mutations here will code for same amino acid

109
Q

What is typically the start amino acid codon?

A

AUG- Methionine

110
Q

What bond usually binds the amino acids?

A

polypeptide

111
Q

What is gene expression?

A

when genes are transcribed and translated into a protein

112
Q

What is first step of transcription?

A

single strand of RNA copy of the DNA is made

113
Q

What is the 1 strand of the DNA used in transcription called?

A

template strand

114
Q

mRNA is what in sequence to the template strand

A

complementary except if there was a T, there is now a U

115
Q

What is a transcription unit?

A

a gene

116
Q

What is the enzyme that unzips and reads the DNA strand?

A

RNA polymerase

117
Q

How does RNA polymerase know what to copy?

A

In sequence there is an area called promotor that the RNA polymerase is attracted to

118
Q

In what direction, 3’ and 5’ is RNA

A

5’ to 3’ (opposite of template)

119
Q

how are the bases of nucleotides linked together?

A

phosphodiester bond

120
Q

What is the promoter?

A

DNA sequence (approximately 40 bp) where RNA polymerase binds

121
Q

Where is the promoter located on the DNA

A

upstream of area needed to be transcribed

122
Q

What is the second step of RNA synthesis?

A

RNA polymerase unwinds DNA to expose single strands and nucleotides bind to the complementary base on the template strand

123
Q

Where does the DNA get unzipped?

A

Only in area of RNA polymerase

124
Q

What causes the RNA to fall off?

A

terminator sequence

125
Q

Where is terminator sequence located on DNA

A

after the stop codon on DNA

126
Q

Eukaryotes have how many different RNA polymerases?

A

3

127
Q

In comparing eukaryotic vs prokaryotic transcription, eukaryotic promoters are what?

A

more varied and complex

128
Q

What are the three RNA polymerases?

A

I, II, III

129
Q

Where is RNA pol I found and what does it synthesize?

A

Found in nucleolus and synthesizes rRNA

130
Q

Where is RNA pol II found and what does it synthesize?

A

Found in nucleus and synthesizes mRNA

131
Q

Where is RNA pol III found and what does it synthesize?

A

found in nucleus and synthesizes tRNA

132
Q

For each RNA polymerase there is what in regards to promoter?

A

each has a different type

133
Q

How is each promoter unique?

A

has a unique sequence that allows the different polymerases to bind

134
Q

For eukaryotic transcription, what is often required?

A

transcription factors

135
Q

What are transcription factors?

A

small proteins that bind to the promoter BEFORE RNA polymerase
often necessary for RNA polymerase binding

136
Q

Where does transcription start and stop? What events…

A

promoter to terminator sequence (hair pin formation)

137
Q

Before RNA is transported out into the cytoplasm, what must first happen?

A

gets processed

138
Q

When is RNA processing?

A

after transcription but before translation

139
Q

What is RNA processing?

A

series of chemical modifications to primary transcript

140
Q

What is first step in mRNA processing?

A

Addition of 5’ cap (additional guanine base)

141
Q

What is the importance of adding a 5’ cap?

A

this is what will be recognized by ribosome once sent out into cytoplasm
also protects mRNA from degradation

142
Q

What is the second step in mRNA processing?

A

Addition of poly (A) tail to 3’ end

143
Q

How many Adenosines are added to 4’ end?

A

50-250

144
Q

What is the importance of adding poly tails

A

protects mRNA from degradation from 3’ end and helps export out of nucleus

145
Q

What is the third step of mRNA processing?

A

Removal of introns

146
Q

What are exons?

A

sequences that code for protein

147
Q

What are introns?

A

non coding sequences that can be quite large

148
Q

What is the process of removing introns known as?

A

RNA splicing

149
Q

How does RNA splicing lead to diversity?

A

in alternative splicing when particular sequences are left in or out which leads to different coding for proteins

150
Q

Where do introns go?

A

Once removed it is broken down into single nucleotides and reused

151
Q

What is the mechanism called that removes the introns?

A

spliceosome

152
Q

Is RNA Splicing Random?

A

No, proteins that do cleaving bind to and splice exactly at the edge

153
Q

Which is there more of in a chain, exons or introns?

A

Always one more exon than intron

154
Q

What are genes?

A

DNA sequences that code for proteins

155
Q

Where are genes found?

A

Hundreds are on each chromosome which are found in the nucleus

156
Q

Where does protein synthesis occur?

A

the information contained in genes must be provided to the ribosomes and this information is provided in the form of mRNA

157
Q

What are the 4 components translation involves?

A

mRNA
ribosomes
tRNAs
Variety of small protein “factors”

158
Q

How are the sequences in the mRNA translated to make a protein? (process)

A

translation

159
Q

Ribosomes are composed of how many subunits?

A

2 (1 small/ 1 large)

160
Q

What are the subunits of ribosomes made of?

A

protein and rRNA

161
Q

How binding sites does ribosomes contain?

A

4

162
Q

What are the 4 binding sites on ribosomes?

A

mRNA, A, P, E

163
Q

What is the adaptor molecule between mRNA and the amino acid

A

tRNA

164
Q

What are contained on the ends of tRNAs

A

anticodon and amino acid

165
Q

How many enzymes for each possible tRNA

A

1

166
Q

What drives the attachment of ribosome to mRNA

A

complementary base pairs

167
Q

Which way down the mRNA does the ribosome move?

A

5’ to 3’

168
Q

How does the ribosome know where to bind?

A

there is a sequence that ribosomes recognize and bind to

169
Q

What is the first step of translation?

A

Intiation- factors and ribosomes assemble upstream of start codon

170
Q

What is the start codon?

A

AUG- methionine

171
Q

What is the second step of translation?

A

Elongation- tRNA binds in A site, amino acid chain is passed to amino acid on new tRNA, tRNAs shift, old tRNA leaves exit site

172
Q

What is the third step of translation?

A

When the ribosome encounters a stop codon

173
Q

What happens when the ribosome encounters a stop codon?

A

a release factor protein binds instead of tRNA and causes the amino acid chain to release

174
Q

What are the two sites that translation can occur?

A

on rough er or out in cytoplasm

Biology Test 2 (2 decks)

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