Exam1 Flashcards
1
Q
What are the four major types of biomolecules?
A
- Lipids (fats)
- Proteins (building blocks from amino acids)
- Nucleic acids (DNA, RNA)
- Carbohydrates (sugars and starches)
2
Q
How are lipids different from the other 3 types of molecules?
A
They are all hydrophobic
3
Q
List the biological functions of nucleic acids.
A
- repositories and transmitters of genetic information
- energy exchange: ATP & GTP
- Metabolic regulation
- Catalytic (some)
4
Q
List the biological functions of proteins.
A
- “workhorse” of the cell
2. structure, movement, catalysis, antibodies
5
Q
List the biological functions of carbohydrates.
A
- energy cycle of biosphere
- structural (cellulose in woody plants, exoskeletons in insects)
- molecular recognition
6
Q
List the biological functions of lipids.
A
- structural - membranes
- energy storage and insulation (fats)
- vitamins - A, D, E,& K
- steroid hormones & eicosanoids
7
Q
Describe the scientific method
A
observe -> hypothesis -> experiment -> observation
8
Q
define hypothesis
A
tentative explanations
9
Q
What are the possible outcomes of an experiment (relative to the hypothesis)?
A
reject or support…NOT prove
10
Q
What are the four characteristics of life?
A
- complexity, with precise spatial organization on several scales
- the ability to change in response to the environment
- the ability to reproduce
- the capacity to evolve
11
Q
What characteristics do the living and nonliving world share?
A
- the same chemical foundation
2. the same physical laws
12
Q
What is thermodynamics?
A
the study of energy and its transformations
thermo = heat
dynamics = power
13
Q
State the first law of thermodynamics
A
- energy can neither be created nor destroyed
- it is transformed from one form to another
14
Q
State the second law of thermodynamics
A
- the degree of disorder in the universe tends to increase
- the amount of disorder is the entropy of a system
15
Q
Define atomic mass and atomic number
A
atomic mass - sum of protons and neutrons
atomic number - number of protons
16
Q
What are covalent bonds?
A
two atoms share a pair of electrons in a molecular orbital
17
Q
polar covalent bonds are …
A
characterized by the unequal sharing of electrons due to large electronegativity differences
18
Q
nonpolar covalent bonds are …
A
characterized by the equal sharing of electrons
19
Q
What are hydrogen bonds?
A
an interaction of a hydrogen atom and an electronegative atom
- weak bonds, but help stabilize biological molecules
20
Q
What are ionic bonds?
A
one atom steals an electron from the other atom. the two atoms are attracted to each other due to the formal charge between them.
21
Q
The chemical structure of water:
A
+H – O-
+H /
22
Q
Define hydrophobic
A
- water-fearing
- do not dissolve in water
- nonpolar
23
Q
Define hydrophillic
A
- water-loving
- dissolves in water
- polar
24
Q
Define amphipathic
A
molecules that contain one or more hydrophobic and one or more hydrophillic region
25
The hydrophobic effect
the tendency for hydrophobic molecules to cluster together to exclude water molecules
26
Self-dissociation of water equation
H2O OH- + H+
27
Value of Kw =
1x10^(-14) = [H+][OH-]
28
What are the concentrations of H+ and OH- in pure water?
```
[H+] = 1x10^7
[OH-] = 1x10^7
```
29
Define acid
molecule that acts as a proton donor
30
Define base
molecule that acts as a proton acceptor
31
Ex of strong acid
HCL
32
Ex of strong base
NaOH
33
pH scale
low pH = acidic
| high pH = basic
34
pH =
-log([H+])
35
pOH =
-log([OH-])
36
pH+pOH =
14
37
What are the four major elements found in biological molecules?
- carbon
- oxygen
- hydrogen
- nitrogen
38
How many covalent bonds does a carbon atom make?
4
39
Diversity of carbon atom
- 4 covalent bonds
- link with each other to form long chains that can be branched or form a ring structure
- double bond with adjacent carbons (prevents flexibility and rotation)
- Isomers
40
List the the functions of nucleic acids
main: form long, linear polymers for encoding, transmitting, and expressing genetic information
other: energy exchange, metabolic regulation, catalytic
41
Griffith's experiment and conclusion:
added dead virulent cells to nonvirulent cells, and some of the nonvirulent cells became virulent. Conclusion: some type of molecule carried the genetic information
42
Experiment by Avery, MacLeod, and McCarty and conclusion:
concluded that DNA carried the genetic information
43
What is the Central Dogma of Biology?
DNA is transcribed into RNA and that RNA is translated into protein
44
What are the three parts to a nucleic acid?
- 5-carbon sugar
- a base
- one or more phosphate group
45
Which carbon in the sugar ring is linked to the phosphate group?
The 5' carbon
46
What are the four bases found in DNA?
Adenine (A)
Guanine (G)
Thymine (T)
Cytocine (C)
47
Which bases are purines?
- double ring structures
| Adenine and Guanine
48
Which bases are pyrimidines
- single ring structures
| Thymine and Cytosine
49
What is a nucleoside?
the combination of a sugar and base
50
What is a nucleotide?
a nucleoside with one or more phosphate groups
51
What is a phosphodiester bond?
- each nucleotide sugar is linked to the phosphate group of the neighboring nucleotide
- the C - O - P - O - C linkage connecting two nucleotides
52
What is the chemical sense of a nucleotide?
5' - 3'
53
Describe the major features of the DNA double helix
- the sugar-phosphate backbone winds around the outside of the molecule and the bases point inwards
54
What is the pattern of hydrogen bonding between bases in the double helix?
complementary base pairing:
A-T
G-C
55
Other than hydrogen bonds, what forces holds together the double helix?
base stacking - non-polar bases stacking as tightly as possible
56
What are the differences between DNA and RNA?
DNA - A, T, C, G - monophosphate - large - double stranded
| RNA - A, U, C, G - triphosphate - small - single stranded
57
What evidence supports the RNA World hypothesis?
1. RNA used in key cellular processes (DNA replication, transcription, and translation)
2. Experiments have shown that RNA can evolve over time
3. Can act as a catalyst (ribosomes)
58
What are proteins?
working molecule of the cell
59
What are some of the cellular functions of proteins?
- carry out the program of activities encoded by genes
- enzymes - catalyze thousands of reactions (specific and fast)
- regulatory, structural, protective roles
60
What are the two major categories of proteins and how do they differ?
Fibrous: non soluble in water, no backbone folding
Globular: soluble in water, folded into spherical shape
61
What is the general structure of an amino acid?
- a central alpha carbon
- an amino group
- a carboxyl group
- a hydrogen
- and an R group
62
Hydrophobic amino acids:
- nonpolar
| - provides energy for protein folding
63
Hydrophilic amino acids:
- polar
| - tend to be on the surface of proteins interacting with aqueous solutions
64
Acidic amino acids:
donate a proton and become negative
65
Basic amino acids:
take a proton and become positive
66
What is special about the amino acid glycine?
- R group is Hydrogen
- no chiral
- non polar and small, increases flexibility of the polypeptide backbone
67
What is special about the amino acid proline?
- R group is linked back to the amino group
| - restricts rotation and puts constraints on protein folding
68
What is special about the amino acid cysteine?
- contains a -SH group
| - 2 cysteine can form covalent bond (disulfide bond)
69
How is the peptide bond formed?
the carboxyl group of one amino acide reacts with the amino group of another acid, and a molecule of water is released
70
What is the sense of a protein?
N-term vs C-term
71
Protein Primary Structure:
- the sequence of amino acids
- determines the 3D structure and properties
- held together by peptide bonds
72
Protein Secondary Structure:
- results from interactions between stretches of nearby amino acids
- result of hydrogen bonding patterns in the backbone of the polypeptide
73
Protein Tertiary Structure:
- the 3D shape of a protein
- determined by spatial distribution of hydrophilic and hydrophobic side chains along the molecule as well as by chemical bonds and interactions that form between the side chains
74
Protein Quaternary Structure:
- the result of protein sub units interacting with one another
- when tertiary structure come together to form a single protein
75
What are the two common types of secondary structure in proteins?
- alpha helix
| - beta sheet
76
What is considered the "backbone" of a protein?
The peptide linkages, along with the alpha-carbon atoms to which R-groups are attached
77
What method is commonly used to determine the structure of a protein?
x-ray crystallography
78
How did the cell get its name?
Robert Hooke thought they looked like cells in a monastery
79
What is the Cell Theory?
1. Cells are the fundamental units of life; a cell is the simplest unit capable of independent existence
2. A living thing is made of cells
3. All cells come from preexisting cells
80
Why are cells so small?
smaller objects have a greater surface/volume ratio and therefore have better communication with the environment
81
What are the structural differences between prokaryotic and eukaryotic cells?
Prokaryotes are smaller and have no organelles
| Eukaryotes are bigger and have organelles
82
What are the main features of the typical prokaryotic cell?
- Chromosomal DNA
- Plasmid DNA
- Cytoplasm
- Ribosome
- Flagellum
- Cell wall
- Plasma membrane
83
List three cellular features of plant cells that are not found in animal cells
1. Vacuoles
2. Cell Wall
3. Chloroplasts
84
What is the endomembrane system?
organelles that communicate with each other:
- nuclear envelope
- endoplasmic reticulum
- Golgi apparatus
- lysosomes
- plasma membrane
- vesicles that move between them
85
Cell membrane/cell wall function
provides additional support for the cell, creates a barrier between the cell and the outside world.
86
Cytoplasm vs cytosol
cytoplasm: cell contents
cytosol: everything in cytoplasm except organelles
87
Ribosome function
protein sysnthesis
88
Nucleus function
protect fragile DNA
89
Cytoskeleton function
give shape and provide movement
90
Cytoskeleton types
- microtubules
- actin filaments
- intermediate filaments
91
Endoplasmic Reticulum function
produces many lipids and proteins
92
Smooth Endoplasmic Reticulum function
site of fatty acid and phospholipid sysnthesis
93
Rough Endoplasmic Reticulum function
sites of protein sysntesis
94
Golgi apparatus function
1. modify proteins and lipids produced in the ER
2. sort proteins and lipids as they move to their final destination
3. glycosilation - synthesize the cell's carbohydrates
95
Lysosome function
degrades polymers into monomeric building blocks
96
Mitochondria function
harness energy from chemical compounds and convert it into ATP
97
Chloroplast function
capture the Sun's energy to synthesize simple sugars for use in the plant cell and in photosynthesis
98
Which organelles are surrounded by a double membrane?
mitochondria
chloroplasts
nucleus
99
How are proteins directed to the proper part of the cell?
Signal sequences: no signal peptide, amino terminal signal, and internal signal
100
What is the function of the signal recognition particle (SRP)?
binds to the ribosome, causing translation to pause
101
```
Which of the following is not a macromolecule?
A. carbohydrates
B. water
C. nucleic acids
D. proteins
E. lipids
```
B. water
102
A hypothesis in biology is best described as:
A. a possible explanation of an observation
B. an observation that supports a theory
C. a general principle that explains some aspect of life
D. an unchanging statement that correctly predicts some aspect of life
A. a possible explanation of an observation
103
A scientific theory is:
A. a guess about how things work in the world
B. a statement of how the world works that is supported by experimental data
C. a belief held by many scientists
D. both a and c
B. a statement of how the world works that is supported by experimental data
104
```
Amino acids are the monomers of _______.
A. nucleic acids
B. proteins
C. carbohydrates
D. lipids
```
B. proteins
105
The cell theory states:
A. cells are small
B. cells are highly organized
C. there is only one type of basic cell
D. all living things are made up of cells
D. all living things are made up of cells
106
The property that distinguishes one atom from another atom is:
A. the number of electrons
B. the number of protons
C. the number of neutrons
D. the combined number of protons and neutrons
B. the number of protons
107
```
Which of the following eukaryotic cellular structures are enclosed by a double membrane?
A. ribosome and nucleolus
B. ribosome and nucleus
C. mitochondria and nucleus
D. mitochondria and lysosome
```
C. mitochondria and nucleus
108
Which three cellular components are present in both prokaryotes and eukaryotes?
A. ribosomes, chloroplasts, mitochondria
B. nucleus, ribosomes, RNA
C. RNA, DNA, ribosomes
D. endoplasmic reticulum, DNA, RNA
E. mitochondria, DNA, RNA
C. RNA, DNA, ribosomes
109
```
The chemical bond between water molecules is a _____ bond.
A. ionic
B. nonpolar covalent
C. polar covalent
D. hydrogen
```
D. hydrogen
110
Which of the following are characteristic of biological systems?
A. high degree of chemical complexity
B. high degree of organization
C. ability to sense and respond to environment
D. highly regulated
E. all other choices are true
E. all other choices are true
111
The First Law of Thermodynamics simply states that:
A. energy is constantly being created in the universe.
B. disorder in the universe is continually increasing.
C. energy can be created but not destroyed.
D. energy can neither be created nor destroyed, just changed from one form to another.
E. energy can be recycled through the universe
D. energy can neither be created nor destroyed, just changed from one form to another.
112
```
Nonpolar molecules tend to aggregate in water because they are forced to come into close
proximity with each other due to:
A. ionizing interactions
B. hydrophilic interactions
C. hydrophobic interactions
D. dissolving interactions
```
C. hydrophobic interactions
113
```
Compared with a pH of 7, a solution of pH 5 has:
A. 1/100 of the hydrogen concentration
B. 5/7 of the hydrogen concentration
C. very nearly the same concentration
D. 2 times the hydrogen concentration
E. 100 times the hydrogen concentration
```
E. 100 times the hydrogen concentration
114
```
A peptide bond is found in _______.
A. proteins
B. lipids
C. carbohydrates
D. only fats
E. nucleic acids
```
A. proteins
115
You arrive late to a biological seminar. However, just as you enter the room, you hear the
speaker referring to the "amino end" and the "carboxyl end" of a macromolecule. Immediately,
you know that they are talking about a:
A. carbohydrate
B. protein
C.DNA
D. lipid
B. protein
116
```
Proteins are created with:
A. phosphodiester bonds
B. peptide bonds
C. a phosphate and two fatty acids bonded to glycerol
D. sugar polymers
```
B. peptide bonds
117
```
The α helix and β pleated sheet represent _____ structure in proteins.
A. primary
B. secondary
C. tertiary
D. quaternary
E. polymer
```
B. secondary
118
Defects in which of the following structures are responsible for a condition called “exercise
intolerance,” where individuals suffer extreme fatigue from minimal exertion?
A. mitochondrion
B. ribosome
C. endoplasmic reticulum
D. Golgi apparatus
E. lysosome
A. mitochondrion
119
Which of the following sequences of events correctly describes the progress of a protein that will
be secreted from the cell?
1. SRP binds to the growing polypeptide chain and to the ribosome.
2. Translation resumes.
3. SRP binds to its receptor.
4. The signal sequence is cleaved.
5. Protein synthesis begins in the cytosol.
6. Translation pauses.
A. 5 -> 1 -> 6 -> 3 -> 2 -> 4
B. 5 -> 6 -> 1 -> 3 -> 2 -> 4
C. 3 -> 6 ->1 -> 2 -> 4 -> 5
A. 5 -> 1 -> 6 -> 3 -> 2 -> 4
