Midterm 1 Flashcards
1
Q
Define Tissue
A
Groups of cells with the same function ( e.g. nerve cells)
2
Q
Define organ
A
Structure composed of several different types of tissues (e.g. heart)
3
Q
nucleotide
A
- Adenine
- Guanine
- Thymine
- Cytosine
4
Q
What is a gene?
A
Segments of DNA molecule that code for a particular protein.
5
Q
What is the correct sequence of DNA to protein?
A
6
Q
What are the 3 domains that all living things can be grouped into?
A
- Bacteria
- Archaea
- Euarya
7
Q
What are the main steps in the scientific method?
A
- Make observations
- Ask a question
- Form Hypotheses (multiple hypothesis) using inductive reasoning (based on observations)
- Make predictions using deductive reasoning (based on hypothesis)
- Test using controlled experiments
8
Q
Define independent variable
A
The variable that is manipulated
9
Q
Define control treatment
A
Experimental subjects exposed to “normal” level of independent variable.
10
Q
Define experimental treatment(s)
A
Experimental subjects exposed to different levels of independent variable.
11
Q
Define dependent variable
A
After experiment has taken place, the dependent variable is what happens as a result of various levels of independent variable.
12
Q
Define comparative test
A
Experimental subjects that were “naturally” exposed to various levels of independent variable.
13
Q
- What if results are as predicted?
- What if results are not as predicted?
A
- Hypothesis is “consistent” with evidence
- Hypothesis is “rejected” and think up new hypotheses
Note: We can never PROVE that a hypothesis is true! All we can do is reject incorrect hypotheses, and find hypotheses that are consistent with the evidence.
14
Q
What makes a hypothesis “scientific”?
A
It has to be testable, that is, potentially able to be rejected.
15
Q
Define macromolecule
A
“Big”, more than 1,000 atoms
Note: Most proteins, nucleic acids, and carbohydrates are macromolecules
16
Q
Define Polymer
A
Long chainlike molecule consisting of monomers linked together by covalent bonds
17
Q
How are monomers linked together to form a polymer?
A
Covalent Bonds
18
Q
How are proteins polymers made?
A
Covalently bonded amino acid monomers
19
Q
How many different types of amino acid monomers exist?
A
20
20
Q
How are nucleic acids polymers made?
A
Covalently bonded nucleotide monomers
21
Q
How are carbohydrate polymers made?
A
Covalently bonded monosacchardies
22
Q
How are polymers built?
A
Dehydration reaction which removes an H2O molecule to form a new bond. Monomers are added to the chain
23
Q
How are polymers broken down?
A
Hydrolysis reaction which breaks covalent bonds by adding an H2O molecule.
24
Q
Define polypedtide
A
A polymer of up to 20 different kinds of amino acid monomers.
25
What determines protein structure?
Side chain (R)
26
How are amino acids linked together?
By a covalent bond between an amino group and carboxy group
27
Define Peptide Bond
A bond between an amino group and a carboxyl group.
Note: Two or more linked amino acids form a polypeptide
28
What is the difference between a protein and polypeptide?
**Polypeptide** - a polymer of amino acids
**Protein** - one or more polypeptides that are folded or coiled into a complex 3-D shape.
29
What is Primary Structure (1º)
The sequence of amino acids in the polypeptide chain.
Note: The order of amino acids with their particular side chain determines the protein's structure at next levels.
30
What is secondary structure (2º)
Regular, repeating coiling or folding patterns in a polypeptide chain. Hydrogen bonds between parts of polypeptide **backbone.**
31
What is tertiary structure (3º)
3-D foldings of polypeptides existing secondary structure stabilized by interactions between the **side-chains**.
32
What is Quaternary Structure (4º)
If protein consists of **two or more** polypeptides form this particular structure.
Note: Most proteins don't have quaternary structure since they are composed of only one polypeptide.
33
What is the main determanant of higher levels of structure, and thus function, of a protein?
Primary structure
Note: a difference in a single amino acid in primary structure will effect higher levels.
Example: Sickle Cell
34
What are the 3 parts that make up a nucleotide?
1. Nitrogen-containing **Base** (AGCTU)
2. Pentose (5-carbon) **Sugar** (RNA-ribose, DNA-deoxyribose)
3. **Phosphate** group
35
What is the difference between a nucloside and a nucleotide?
Nucleoside = one base + one sugar
Nuclotide = one nucloside + a phosphate group
36
How are nucleotides linked to each other?
A covalent bond between a _phosphate_ group of one and the _sugar_ group of the next.
This bond is called a _phosphodiester bond_. Creating a "sugar-phosphate" backbone, with bases sticking out the side.
The 5’ end has a phosphate group and the 3’ end has a hydroxyl group (OH)
37
What is DNA composed of and how is it oriented?
DNA is composed of two strands of nucleotides oriented in opposite directions.
38
How are two strands of DNA held together?
By hydrogen bonds between complementary base pairs.
A-T
G-C
39
Sort DNA bases into purines and pyrimidines.
Purines: Adenine (A) and Guanine (G)
Pyrimidines: Thymine (T) and Cytosine (C)
A-T
G-C
40
What is the primary purpose of DNA?
Information-containing molecule which is encoded in the sequences of bases (ATGC)
41
What are the products of DNA replication?
1 DNA double helix produces 2 identical double helices
42
What is RNA and how is it formed?
A nucleic acid that contains same information as DNA. Formed by **transcription** from one of the two strands of a DNA double helix.
43
How is RNA different from DNA?
1. Sugars are ribose, not deoxyribose
2. Uracil (U) is used instead of thymine
3. RNA is single-stranded thus does not form double helices
44
What are the products of RNA transcription?
1 DNA double helix produces 1 DNA double helix + 1 Single stranded RNA
45
What is the central dogma of molecular biology?
1. DNA can reproduce itself (replication)
2. DNA can copy its information into RNA (transcription)
3. RNA can specify a sequence of amino acids in a polypeptide (translation)
46
For the bond between two carbohydrate monomers (monosaccarides), how is it bonded and what is the bond called.
A covalent bond called a glycosidic bond.
Two linked sugars are disaccharides
47
What are some main functions of lipids?
1. Energy source
2. Cell membrane structure
3. Key base components of important hormones
48
What are fats (triglycerides) composed of?
Glycerol + 3 fatty acids bound by ester bonds
49
What are phospholipids composed of?
Glycerol + 2 fatty acids, bound by ester bonds, + 1 phosphate containing compound
50
How is mRNA translated into polypeptides?
Amino acids attached to tRNA land on mRNA and then attach to the growing polypeptide. This is mediated by a ribososme.
51
What are tiplet codons?
Sequences of 3 nucleotides that code for a specific amino acid.
52
Describe the relationship between a protein, polypeptide and amino acid?
Amino acids are the basic unit of proteins.
Amino acids linked together by a peptide bond forms a chain of amino acids called a polypeptide. When the amino acids from different parts of the chain interact with each other and form hydrogen bonds, the polypeptide chain takes on a unique shape, forming a protein.
53
Why are most cells so small?
Surace area (ability)-r2 / Volume (need)-r3
So as r increases, the need for new material becomes too great for the ability to supply it.
54
Name 3 things microscopes do
1. Magnify - make image larger
2. Increase resolution - minimum distance two points can be seen as two distinct objects
3. Increase contrast - brightness difference between object and background
55
What is the difference between light microscopy and electron microscopy?
Light Microscopy uses beams of light : max resolution = 0.2 micro meters
Electron Microscopy uses beams of electrons: max resolution = 0.002 micro meters
56
Name two types of light microscopy
1. Brightfield LM - light passes through specimen
2. Fluorescence - light striking specimen excites fluorescent molecules
57
Name two types of electron microscopy
1. Scanning EM - electron beam energizes electrons on specimen surface
2. Transmission EM - electrons pass through a thin secion of specimen
58
Name some common features of Prokaryotic and Eukaryotic cells
1. All cells bounded by a selectively permeable _plasma membrane_ (phospholipid bilayer with proteins and molecules embedded)
2. All cells contain _cytosol_
3. All cells contain _ribosomes_ made of ribosomal RNA (rRNA) and protein
59
What is cytoplasm made of?
Cytosol + particles
60
Name 7 unique featurs of prokaryotic cells
1. Very small: 1-10 micro meters
2. Unicellular (but often found in groups)
3. Various shapes: baccillus, coccus, and spirals
4. No membrane bound organelles
5. DNA is nucleoid region (not membrane-enclosed)
6. Have flagella for movement and fimbriae (pili) for attachment
7. Rigid cell wall outside plasma membrane
61
What is the main difference between cell wall of Bacteria and Archaea
Bacteria - cell wall contains **peptidoglycan** (lysozyme effective on)
Archaea - cell wall contains **pseudopeptidoglycan** (lysozyme not effective)
62
Name unique features of Eukaryotic cells
1. Large 10-100 micro meters
2. Contains organelles
3. Contains cytoskeleton (microfilaments, intermediate filaments, microtubules)
4. Contains a **nucleus** surrounded by 2 phospholipid bilayers
63
What is a chromosome
Each DNA molecule is called a chromosome
64
Define chromatin
A double-stranded DNA molecule (chromosome) wrapped around histones
65
What is the function of the nucleolus?
Make **ribosomes**
66
What happens to DNA inside the nucleus?
1. DNA replicated
2. DNA transcribed into mRNA (which exits to the cytoplasm via nuclear pores)
3. Ribosomes are made (in nucleolus) and exit to cytoplasm via nuclear pores
67
What is endoplasmic reticulum?
Rough ER (ribosomes) - Protein synthesis
Smooth ER - Lipid synthesis, carbohydrate metabolism
68
What is the Golgi aparatus?
Proteins from ER are sent to golgi aparatus in vesicles for modification/ packaging/ and are sent elsewhere
69
What are lysosomes?
Membrane-bound vesicles used to digest food/recycle old cell components
70
What are some key characteristics of mitochondria?
1. Perform cellular respiration for energy
2. Contain their own DNA and ribosomes (divide independently)
3. Contain outer and inner membrane
Note: Found in most all eukaryotes (INCLUDING PLANTS)
71
What are plastids?
1. Only found in plant cells
2. Have their own DNA and ribosomes (replicate independently)
eg. chloroplasts, chromoplasts, amyloplasts
72
Name 3 motor proteins involved in movement in eukaryotic cells
1. Myosin - single cells
2. Kinesin - organelles
3. Dynein - cilia/flagella (9+2 arrangment)
73
What is the extracellular material in both eukaryotes and prokaryotes?
Animal cells: Extracellular matrix (ECM)
Plant cells: Cell wall made of **cellulose**
Prokaryotes: **rigid cell well** (some bacteria have a **capsule** of polysaccharides)
74
What is serial endosymbiosis theory?
The theory that mitochondria and plastids originated by endosymbiosis - when and ancestral eukaryote engulfed a prokaryote but did not digest it. Mitochondria first then plastids
75
What protein do microtubules mostly consist of?
Tubulin
76
What protein do microfilaments mostly consist of?
Actin
77
What is the endomembrane system and how can it expain how eukaryotes evolved from prokaryotes?
Endomembrane system just means the different membranes (organelles) suspended in cytoplasm. It may have originated from **inward folds of the plasma membrane** of prokaryotes. Compartmentalization is favored for various chemical reactions to take place simultaneously.
78
What are the 4 events that must occur in ALL types of cell division?
1. A reproductive signal
2. Replicate DNA
3. Segregation
4. Cytokinesis
79
How to prokaryotes divide?
Binary fission - parent cell divides to from **2 genetically identical** daughter cells
80
Can prokaryotic organisms be multicellular?
No
81
Can eukaryotic organisms be unicellular?
Yes but it is rare
82
What is the result of Mitosis
A parent cell divides to form **2 genetically identical** daughter cells
83
What is the result of Meiosis?
A parent cell divides to form **4 genetically different** daughter cells that have **half the number of chromosomes** as the parent.
84
What is the reproductive signal to initiate binary fission?
Cell size which is controlled mainly by environment (food, temperature)
85
How does DNA replication occur during binary fission?
Ori - where replication starts
Ter - where replication ends
At **ori site**, the two strands of double helix DNA are seperated and replicated eventually ending at the **ter site**.
86
How does segregation occur during binary fission?
When DNA replication beings, the 2 ori sites get attached to **opposite ends** of the plasma membrane
87
How does cytokinesis occur during binary fission?
After replication, plasma membrane pinches in and cell wall is secreted between 2 new cells
88
Describe chromosomes before and after the S phase?
Before: **1** DNA molecule (1 chromosome)
After: **2** joined DNA molecules, or sister chromatids (1 chromosome)
89
What are two important signaling molecules at checkpoints in the eukaryotic cell cycle?
**Cyclin** and **C****yclin-dependent kinases (Cdk)**
Cdk is always present but is inactive until cyclin binds to it, which allows for Mitosis.
90
Define nucleosome
A "bead" on the chain of chromatin
91
Define centromere
Where two sister chromatids are attached
92
Define centrosome
A **region** that organizes microtubules
Contains a **pair of centrioles** composed of 9 sets of 3 microtubules each.
Note: After S phase, there are two centrosomes present
93
What happens during Prophase?
1. Chromatin condenses
2. Nucleolus disappears
3. Centrosomes form **asters** and **mitotic spindle** and move toward opposite sides
94
What happens during Prometaphase?
1. Nulcear envolope breaks down
2. Kinetochores from centromeres interact with kinetochore microtubules
Note: There are kinetochore microtubules and nonkinetochore microtubules
95
What happens during metaphase?
Centromeres align on metaphase plate
96
What happens during Anaphase?
Sister chromatids pulled toward opposite sides by kinetochore microtubules
97
Telophase
1. Nuclear envolop re-forms
2. Chromosomes uncoil
3. Spindle dissapears
4. Cytokinesis begins
98
How does cytokinesis differ between animal and plant cells?
Animal: A "contractile ring" of **actin** tightens due to myosin forming a **cleavage furrow**
Plant: Forms **cell plate** at midline
99
What is the difference between the cell walls of plant and animal cells?
Animal: **Non-rigid** cell wall
Plant: **Rigid** cell wall
100
How to interactions between motor proteins and cytoskeletal proteins facilitate movement?
1. **Myosin** pulls on **actin** to make cells contract
2. **Kinesin** attaches to organells and microtubules
3. **Dynein** moves microtubules relative to each other in **cilia/flagella**
101
What is asexual reproduction?
**1** parents produces offspring that are **genetically identical**
102
Somatic cells
Cells that make up the body of an organism and are NOT used for sexual reproduction. (eg. liver, heart)
Somatic cells contain two sets of homologous chromosomes - one maternal one paternal
103
Define homologous chromosomes
Chromosomes that carry the **same genes** but may have **different alleles** (versions of that gene).
104
Autosomes vs Sex chromosomes
Autosomes - chromosomes that have same set of genes
Sex chromosomes - may differ! X is different from Y
105
Define locus
Position of a specific gene on a chromosome
106
Diploid vs Haploid
Diploid: Total number of chromosomes (2n)
Haploid: Half the number of chromosomes (n)
107
What is the Diplontic Life Cycle? (animals)
1. **Gametes (n)** fertilize to make **Zygote (2n)**
2. **Zygote (2n)** undergoes mitosis - forms **multicellular organism (2n)**
3. **Organism (2n)** undergoes Meiosis to form **gametes (n)**
\*The only haploid cells are gametes\*
108
What is the Haplontic Life Cycle? (fungi, protists)
1. **Gametes (n)** fertilized to make **diploid zigote (2n)**
2. **Diploid zigote (2n)** undergoes Meiosis to produce haploid cells **(n)**
3. **Haploid cells (n)** undergo Mitosis forming a **haploid unicellular or multicellular organism (n)** and **gametes (n)**
**\***The only diploid cells are Zigote\*
109
What is the Alteration of Generations Life Cycle? (plants)
1. **Gametes (n)** fertilized to make **diploid zygote (2n)**
2. **Diploid zygote (2n)** undergoes mitosis to form a **diploid multicellular sporophyte (2n)**
3. **Sporophyte (2n)** undergoes **Meiosis** to produce **haploid spores (n)**
4. **Spores (n)** undergo Mitosis to form **haploid multicellular gametophyte (n)**
5. **Gametophyte (n)** undergoes mitosis to produce **gametes (n)**
110
What are the similarities and differences between Propahse (mitosis) and Prophase 1 (meiosis)?
_Similarities_: 1. chromosomes condense
2. spindle forms
3. nuclear envelope breaks
4. kinetochores attach to spindle microtubules
_Differences:_ **Snyapsis** and **crossing over** occurs
111
What is the difference between synapsis and crossing over?
_Synapsis_: homologous pairs of chromosomes **line up next to each other** and **physically attach** via the "synaptonemal complex"
_Crossing over:_ during synapsis, one paternal sister chromatid and one maternal sister chromatid **break at same position** and **swap** genetic information - this process is called **recombination**
112
What is different between Metaphase and Metaphase I?
During metaphase (mitosis) - **individual chromosomes** (sister chromatids) line up
During metaphase I (meiosis) - **homologous paris** line up
113
What is independent assortment?
**Homologous pairs** line up **randomly** on the metaphase plate during Metaphase I
114
What is different between Anaphase (mitosis) and Anaphase I (meiosis)?
Anaphase - sister chromatids are pulled apart
Anaphase I - homologous chromosomes are pulled apart (**sister chromatids remain attached**)
115
What is a nondisjunction?
An error in meiosis leading to **aneuploidy** - abnormal number of chromosomes
116
Why is it extremely unlikely to yeild offspring identical to parents during sexual reproduction?
1. I**ndependent assorment** during Meiosis I
2. **Crossing over** during Meiosis I
3. **Random Fertilization**
117
What is random fertilization?
Sperm picks a random egg
Sperm (223 combinations) X Egg (223 combinations) = 70 trillion unique combinations
118
What is chiasma?
The "crosses" formed when **non-sister chromatids overlap** during crossing over
119
Why is genetic variation, produced by sexual reproduction, important for the survival of a given population?
Because the environment is not stable over time so a population must change over time in order to survive
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