Da Cell Flashcards
1
Q
How do Prokaryotic cells divide?
A
Binary Fission.
2
Q
What are homologs?
A
Chromosome pairs, these may carry different alleles of the same gene.
3
Q
What is the interphase of Mitosis, what are it’s parts.
A
The interphase is the biggest phase of cellular life during which the cell functions and grows and prepares for replication.
G1, S, G2
4
Q
What is interphase G1
A
G1 is the first phase and this is where the cell grows and synthesizes enzymes and proteins necessary to replicate DNA. The cell will either then go into phase S or G0 ( Where it will not divide, this can be temporary or permanent.)
5
Q
What is interphase S
A
S phase is after G1 and is when the cell is committed to divide but must duplicate it’s chromosomes before mitosis, the chromosomes will now have duplicate sister chromatids.
6
Q
What is the G1/S checkpoint.
A
A check point before entering cell division that ensure the cell has all enzymes and proteins for replication of DNA.
7
Q
What is G2
A
G2 is after S phase has some more chemical components prepping for cell division.
8
Q
What is the G2/M Checkpoint
A
This check point ensures all the DNA has been duplicated without any errors or damage.
9
Q
What is the M phase?
A
The M phase is the Cell Division phase and incudes all of Mitosis.
10
Q
What are the stages of mitosis in order?
A
Prophase, Pro-metaphase, Metaphase, Anaphase, Telophase, Cytokinesis.
PPMATC.
11
Q
Prophase?
A
Chromosome condense and the mitotic spindle forms.
12
Q
What is the mitotic spindle?
A
Forms in Prophase and is an array of microtubules that move the chromosomes. In animal cells these form from the centrosomes which split at opposite ends of the cell.
13
Q
Prometaphase?
A
Disintegration of the nuclear membrane, spindle microtubules enter the nuclear region and attach to the sides of the kinetochore on the chromosome, this is two tubules per kinetochore, or one per sister chromatid. This is called Bi-Orientation.
14
Q
Metaphase?
A
The chromosomes will arrange in a single file line at the center metaphase plate and the microtubules begin to have tension on the kinetochores.
15
Q
What is the spindle assembly checkpoint?
A
Occurs during metaphase and ensures each chromosome is aligned on the metaphase plate, and Bi-orientation is achieved and tension is required to pass this checkpoint.
16
Q
Anaphase?
A
This is when the Sister Chromatids split.
17
Q
Telophase
A
Marked by when the sister chromatids meet at opposite ends of the cell at the spindle poles. The nuclear membrane will reform, one at each end, around these now chromosomes. The chromosomes then relax.
18
Q
Cytokinesis
A
This is when the cytoplasm splits (cell wall forms in plant cells) and the cell officially divides into two genetically identical daughter cells, however they may not be identical in cytoplasm/ organelle content.
19
Q
Name two points of Mitosis
A
Produces two genetically identical daughter cells.
Asexual cell type.
20
Q
Name three points on Sexual reproduction
A
Combines genetic material from parents for variable offspring.
Uses Meiosis
Fertilization: two haploid gametes forming a Diploid Zygote.
21
Q
What kind of cells are formed from meiosis?
A
Genetically variable haploid gametes.
22
Q
What are some things in common between meiosis and mitosis?
A
They both have interphase G1, S, G2. Where the DNA is duplicated and goes through the same checkpoints.
23
Q
Prophase 1 Meiosis
A
Chromosomes (2 chromatids) condense, form homologous pairs, synapses form, recombination happens and centromeres start to move away from each other but remain attached at chiasmata. nuclear membrane breaks down and spindle fibers start to appear.
24
Q
What are Homologous pairs of chromosomes?
A
Chromosomes that are the same shape, size and have genes at the same locus’s. One is generally from each parent.
After this the nuclear membranes disintegrate.
25
Metaphase 1 Meiosis
The homologous chromosome pairs align in the center of the cell (no specific oder to which side each chromosome is on creates independent variation.) and spindle fibers begin to attach to the kinetochore of the chromosome on it's corresponding side.
26
What are the Five Stages of Prophase 1 Meiosis?
Leptotene: Chromosomes Condense.
Zygotene: Continue to condense and start synapsis, each of these pairs is bivalent or tetrad.
Pachytene: Chromosome becomes shorter and thicker and form a synaptonemal complex and then recombinate.
Diplotene: The synapse complex breaks down and the centromeres of the pairs will move apart but remain attached at the now formed chiasmata where cross overs occurred.
Diakinesis: Chromosomes finish condensing , the nuclear membrane disintegrates, and spindles start to form.
27
What is the synaptonemal complex?
A protein complex that forms "Railroad track-like fibers" between homologous chromosomes and is thought to assist in recombination.
28
Anaphase 1 Meiosis
Spindle fibers pull apart the homologous chromosomes to each pole of the cell. (The sister chromatids remain attached.)
29
Telophase 1 Meiosis
When the chromosomes (sister chromatids attached.) reach the poles on each side of the cell. The cytokinesis then occurs.
30
What is Interkinesis?
The period between Meiosis 1 and 2 where The nuclear membrane reforms, spindle disappears, and chromosome relax.
31
Prophase 2 Meiosis?
The chromosome re-condense, nuclear membrane disintegrates and the spindle reforms.
32
Do all cells go through interkinesis?
No, in some cells the chromosomes will remain condensed, no nuclear membrane reformation, still have spindles and go right from cytokinesis into metaphase 2 meiosis.
33
Metaphase 2 Meiosis?
The chromosome single file line up at the center metaphase plate and the spindle fibers attach at the kinetochore.
34
Anaphase 2 Meiosis?
The sister chromatids are pulled apart towards the poles of the cell.
35
Telophase
The Chromosomes (sister chromatids.) reach the poles of the cell. The nuclear membrane reforms, the chromosomes relax and cytokinesis occurs.
36
What is the protein cohesin responsible for?
Cohesin is responsible for holding together the sister chromatids along their entire length during mitosis and meiosis. Additionally in meiosis Cohesin holds the homologous chromosomes together at the chiasmata.
37
What is the protein shugosin responsible for?
Shugosin means "guardian spirit in japanese" it guards the cohesin from separase at the centromere keeping sister chromatids together during meiosis 1 and degrades after.
38
What does separase do?
breaks down cohesin causing separation of the homologous chromosomes (shugosin) in anaphase 1 and then separation of chromatids in anaphase 2.
It also breaks down cohesin in mitosis anaphase so the sister chromatids separate.
39
What is non disjunction of meiosis?
A problem with chromosome separation that occurs during metaphase 1 and/ or 2 and will affect the number of chromosomes in the daughter cells.
40
How many sperm are produced from meiosis in mammals?
4 this is called spermatogenesis.
41
how many ovum are produced from meiosis in mammals?
1
42
How does oogenesis occur?
Oogonium enter prophase 1 and become primary oocytes they will stay at this stage until puberty start becoming secondary oocytes (this can span 30-40 yrs) after finishing meiosis 1 there will be a secondary oocyte and a polar body. The oocyte will stay at this stage until fertilization, and then will complete meiosis 2 producing an ovum and a second polar body. The new ovum will then fuse with the sperm and form a zygote.
43
What are the four points of Cell Theory?
- All living organisms are made of cells.
- The cell is the fundamental unit of structure and function in living organisms.
- All cells are essentially the same in chemical composition.
- All cells come from other cells.
44
Are viruses Alive?
No! They cannot reproduce on their own.
They also don't have growth.
45
DNA to RNA?
Transcription!!!
46
RNA to Protein?
Translation!!
47
What molecule was likely not present on earth at first?
When was it produced?
Primitive earth likely lacked O2 and started with anaerobic organisms. It wasn't until photosynthesis that earth became abundant in O2 primarily from cyanobacteria.
48
What were the three processes of early earth allowing for production of organic molecules?
- Heat (sun)
- Electric Discharge (lightning)
- Cooling System (Molecules to liquid form.)
49
What four molecules were produced by "Early Earth Experiments"
- Aldehydes
- Simple Acids (ammonium NH4+)
- Complex Acids (amino acids)
- Long Hydrocarbon Chains. (Fatty Acids.)
50
After organic molecules were produced by the earths atmosphere what likely came next?
Abiotic Earth self replicating macromolecules. RNA world hypothesis. Discovered certain RNA could self replicate.
51
RNA molecule that can also act as an enzyme (usually folded in some way.)
Ribozyme.
52
What are three activities of ribozymes?
- RNA splicing
- Ligation
- Polymerization.
53
What is a ribosome composed of?
rRNA and rProteins.
54
What are the types and functions of RNA?
mRNA- Messenger transcribed RNA that leaves the nucleus with code for proteins.
tRNA- Transfers amino acids to ribosome during translation.
rRNA- Ribosomal RNA, main component of ribosome. in combination with proteins forms large and small sub units that build polypeptide chains.
55
What ribozyme is part of the large ribosomal subunit and assists in forming peptide bonds?
peptidyl transferase.
56
how might ribozymes interact with other RNA molecules?
Ribozymes can cleave RNA (if mRNA, this stops production of that protein.)
Ribozymes can also base pair, and this allows for cleavage at specific sites of the substrate.
57
How did DNA come about?
Hypothesis: Some RNA can self replicate using ribozymes. These RNA's eventually became able to produce proteins. DNA is more stable than RNA but requires many proteins to replicate.
58
What limits the size of cells? excluding frog eggs.
The size of a cell requires more membrane to be produced per unit of volume.
59
Three characteristics of smaller cells in relation to larger cells.
- Smaller cells can interact with surroundings more efficiently.
- Smaller cells lose more heart/ energy to surroundings.
- Smaller cells have higher metabolic rate.
60
Three things prokaryotes lack?
- Cytoskeleton
- Nuclear envelope
- Membrane bound organelles
61
Distinguishing feature of eukaryotes?
Nuclear envelope.
62
Most diverse cell type?
Prokaryotes.
63
Do photosynthetic bacteria have chloroplasts?
NO Membrane bound organelles!! That have a system of membranes where photosynthesis occurs.
64
What is chemosynthetic?
Derives energy from oxidation of H2S
65
Explain mitochondria?
Power house.
Contains mtDNA that is only inherited from mothers side in humans. Thought to have evolved via endosymbiont in an oxygen rich world.
Enclosed by a double membrane very similar to prokaryote, not other organelles, and has circular DNA.
66
Explain chloroplasts
Photosynthesis in eukaryotes, non-animal cells. Believed to be attained via endosymbiont post mitochondria (no plant ancestry W/O mitochondria.)
67
What are the steps of exocytosis?
Product is formed, usually within RER, and "bud" from the membrane as vesicles & travel to the golgi apparatus for packaging, from they travel to the outer membrane of the cell where the vesicle will become part of the cell membrane and release it's contents. They use the cytoskeleton filaments as tracks to the outer membrane.
68
Name one things animals cells have plant cells don't, what is their alternative?
Centrioles, used to organize microtubules.
Plant cells have a microtubule organizing center.
69
What are the four building blocks of the cell?
Sugars, Fatty Acids, Amino Acids, and nucleotides.
70
What are the four larger building units of the cell?
Polysaccharides, fats, lipids, membranes, proteins, nucleic acids.
71
What is a condensation reaction?
Think Dehydration synthesis, water by product. Endergonic (requires energy.) Builds a product.
72
What is a hydrolysis Reaction?
When water is added break down a molecule. Usually adds an H and OH to each piece.
73
What happens when two monosaccharides go through a condensation RXN?
Dehydration reaction, will combine the monosaccharides and have H2O by product, builds a Disaccharide bonded via Glycosidic (covalent) bond.
74
What are the two parts of a fatty acid?
Hydrophilic carboxylic head and Hydrophobic hydrocarbon tail.
75
Difference between a saturated and unsaturated fat?
Saturated= Saturrated W/ Hydrogens- Alkane.
Unsaturated = Double bond/s somewhere- Alkene.
76
How to fatty acids link to glycerol?
an ester bond.
77
Types of fats and differences?
- Saturated fats: Bad, tightly packed, build up in arteries.
- Unsaturated trans fats: WORST unsure how these get processed, raise bad cholesterol, not natural.
- Unsaturated Cis Fats: Best, Raise good cholesterol.
78
Oleic Acid Vs. Elaidic Acid?
Oleic Acid- Cis fat
Elaidic acid- Trans fat
isomers of each other.
79
Describe phospholipid:
Fatty acids + glycerol. Two non-polar tails, one is usually cis bond, other is saturated.
Hydrophilic phosphate group, with a polar group at the head (usually choline)
The more saturated= more rigid.
more unsaturated= more fluidic.
80
Amino Acid.
In the body a (+) on the Amine (NH2) and a (-) on the Carboxylic Acid (COOH)
The R-group Defines the type of amino acid.
The carbon the R-group is attached to is the alpha carbon.
81
How are amino acids bonded?
Through (covalent) peptide bonds, usually formed via condensation (Dehydration).
The blue is by product H20
The Carbon will attach to the Nitrogen.
This creates a Carbon nitrogen backbone with a C and N terminus. (N-C-C)
82
What is ATP?
Adenosine triphosphate, a nucleotide containing Nitrogenous base (adenine), Ribose sugar and triphosphate.
83
Difference between deoxyribose and ribose?
Deoxyribose has lost an Oxygen on the beta carbon. OH group is only on the 3'. Think, DNA can only replicate to the 3' side (5'-->3' direction)
84
What is a nucleotide composed of?
Nucleoside + Phosphate group.
85
How do nucleotides attach?
Always in the 5' Phosphate to 3' OH.
The 5' Phosphate will attach to the 3'OH. These are joined by phosphodiester (covalent) bonds.
The Nitrogenous bases will be joined by hydrogen bonds.
This is now a nucleic acid.
86
What is a nucleoside?
5 Carbon Sugar backbone (D or R) + nitrogenous base.
87
ATP and ADP?
Adenosine (tri- or di- ) phosphate.
ADP has 1 less phosphate group.
Cellular respiration produces ATP, a stored form on energy (currency), When around H20 the third phosphate group will readily separate releasing energy as the OH group adds to the now diphosphate group.
This is a hydrolysis reaction.
88
Hydrolysis Vs Condensation RXN.
Hydrolysis:
-consumes H20
-releases energy.
-breaks things down.
Condensation:
-H20 byproduct
-uses energy.
-attaches molecules.
89
What is a polymer?
A chain of monomeric subunits.
90
When does a polypeptide become a protein?
When the polypeptides come together to a shape that is functional.
91
Does the polypeptide backbone primary structure have free rotation?
The side chain R-groups are able to rotate freely but due to the resonance between O-C-N the C-N back bone bond is rigid.
92
What type of bonds stabilize folding proteins?
weak non-covalent bonds, MANY.
93
Sequence of amino acids protein structure?
Primary.
94
Localized conformations of the polypeptide backbone structure?
Secondary. Alpha helix (H-bonding between every 4 peptide bonds.) & beta sheets, non-covalent bonds such as H-bonding.
No R-group side chain interactions.
95
Folding pattern of an entire polypeptide chain to produce it's
3-dimensional structure.
Tertiary Structure.
Side chain orientation: Hydrophobic non-polar stay to inside.
Hydrophilic polar go to outside of the structure.
cysteine and disulphide covalent bonding.
Structure will determine function.
96
Multiple polypeptides arranged in a specific way Structure?
Quaternary structure. non-covalently bound/ electrostatic interactions.
Usually has sub units that will determine it's function.
97
When non-synonymous mutations occur that affect the amino acids side chains what might happen?
When amino acids side chains are changed, this can affect the intramolecular forces of the protein & subsequently how it folds, which affect it's function.
EX: Sickle cell is just a mutation for Valine instead of glucose & changes the folding pattern at that location & the shape of hemoglobin at large which causes the disc shape which clogs blood vessels and severely limits O2 supply.
98
Name and why special?
Cysteine, non-polar. The H-S
99
What type of amino side chains stay towards the outside of the protein as it folds?
The Polar and Charged amino acids. They are chemically reactive if an aqueous environment.
100
5 steps of protein maturation?
1. Correct Folding
2. Proteolytic Cleavage- cuts off unneeded bits.
3. Chemical Modifications.
4. Formation of Quaternary structures.
5. Association W/ Co factors.
101
In Tertiary structure folding what occurs that allows 3-d folding to begin that was preventing it before?
Chaperones which were bonded to nascent (new) polypeptide during synthesis will begin to release and allow proper folding.
102
What are cross links?
Links between the side chains that can be elastic and help hold together the protein, most common in the disulfide bonding of cysteine. Think of collagen, as they stretch out over time.
103
What can break disulfide bonds?
Reducing agents such as Beta-mercaptoethanol
104
What is urea?
an excrete toxic ammonia metabolic waste product of mammals. A reversible denaturant.
105
What are TSE's?
Transmissible Spongiform Encephalopathies. They are caused by Prions, an infectious agent these are incorrectly folded proteins. They are not recognized to be degraded and are able to alter normal proteins and lead to protein aggregate plaque.
They do not transmit genetic info.
106
What are the two levels of protein regulation?
- Regulation of gene expression: think on/ off for transcription.
- Regulation of protein function- restricted according to the needs of the cell.
107
What is kinase activity?
Phosphorylation, think ATP. This usually requires a binding regulator that will have a binding constant that will affect when kinase activity is active.
108
What are the 6 protein activity regulation types?
1. Reg by location
2. Reg by binding activation
3. Allosteric feed back +/-
4. Phosphorylation- Kinase-uses ATP.
5. GTP binding- hydrolysis GTP-GDP
6. Proteolytic degradation & ubiquitylation.
109
Ubiquitin regulation:
Mono:
Multi:
Poly:
Mono: histone reg
Multi: Endocytosis.
Poly proteasomal degradation usually or DNA repair. Uses ATP.
110
Where is rRNA transcribed?
Nucleolus
111
Where are ribosomes made?
Nucleolus
112
LAD and NAD?
Laminar and nucleolus associated domain. Both are heterochromatin.
113
Cells which will develop into gametes.
Germ line cells.
114
What are the only cells that will be given to offspring from its parents?
Germ line cells and these give rise to the gametes.
115
Any cell that is not a germ line cell?
Somatic Cells.
116
What will a germ line mutation affect?
Only the offspring, this is a heritable trait/ mutation for future offspring as well.
117
What does a non-synonymous mutation within a gene usually lead to?
an altered product/ protein/ amino acid.
118
What does a non-synonymous mutation in the regulatory/ promoter region of DNA usually lead to?
Altered expression/ regulation. (How much, When, Where?)
Affects transcription.
119
What does the promoter region of DNA do? (eukaryote)
it is a region of DNA generally upstream of the gene region. This is where RNA polymerase will bind with the required help of transcription factors that are activators (repressors opposite) to initiate transcription
(DNA--> RNA)
120
What are the results of gene duplication?
Either of the duplicates over time and division may acquire mutations that affect the selection of how either one may be expressed (advantageous or deleterious.)
121
What is an exon?
A region of DNA or RNA that encodes for a protein, The DNA portion encodes the RNA for the exon. This is the portion that will be in mRNA (mature messenger RNA.)
122
What is pre-mRNA?
This is mRNA before it is modified (spliced) in the nucleus. This RNA includes both exons and introns.
123
What is exon shuffling?
Usually occurs during a crossing over event where an exon is involved and can lead to new functions of proteins once made into mRNA. Since introns are removed the crossing over does not have to be precise, more likely to occur when there are longer introns involved.
124
What is transposition?
When a transposon (jumping gene) is transposed into the regulatory region of DNA and may alter the activity/ regulation/ expression. Can promote other genome rearrangements as well.
125
What is horizontal gene transfer?
This is mostly occurs in prokaryotes. When an organism passes a gene to another organism (even diff species.) (Not vertical gene transfer parent to offspring)
126
Mutations can occur in various regions of DNA how would a non- synonymous point mutation likely affect the following?
intron region:
exon region:
regulatory region:
Intron: no effect
Exon: affects the protein product produced (good or bad.)
Regulatory Region: (good or bad) affects production/ expression, when, where. Much larger effect of the organism, usually very deleterious.
127
What is an allosteric site?
This is a site on an enzyme or receptor where it will bind to a molecule (effector) and modify the enzyme's activity.
128
What does allosteric refer to?
Change in the shape/ activity of a protein/ enzyme.
129
A complete non-disjunction event occurs in meiosis in a species germ line cells chromosomes what does this mean for it's offspring?
If the offspring is viable, it will have a different number of chromosomes this is pretty much an immediate speciation event, only if the species is also fertile.
130
What is homeotic transformation?
Type of genetic mutation which leads to a body part being replaced by a body part usually expressed elsewhere.
Think "legs for antennas in melanogaster."
131
What is genetic conjugation?
The horizontal transfer of genetic information from one cell to another through a sex pilus (genetic recombination without reproduction)
132
How are phospholipids able to move in a membrane?
They can diffuse laterally, rotate and have some tail flexion. They do not spontaneously flip sides. (fluid mosaic)
133
How is cholesterol involved in the lipid bilayer membrane?
Cholesterol has a polar head group and rigid steroid structure and hydrocarbon tail, this assists in being a bumper, prevents over packing, balances fluidity to provide some structure.
134
What are two important regulations of cholesterol?
@ high temp: Restrain movement of fatty acids (maintains stability)
@ low temp: Prevents tight packing of fatty acids (maintains fluidity.)
135
What are glycolipids? Where are they found?
Has a saccharride head. and is on the outer extracellular membrane side. Acts as a cell identity marker.
136
What are charged phospholipids?
Where are they found?
Contain a negatively charged phosphate group found on the intracellular side of the membrane.
137
What is a function of Transporters in the cell membrane?
Carrier proteins and ion channels.
Actively pumps Na+ out and K+ into the cell.
138
When net movement is down the concentration gradient and particles can cross the cell membrane freely?
Passive transport:
Simple diffusion. (osmosis)
Gases, small polar/ hydrophobic molecules.
No charged molecules!!
139
When net movement is down the concentration gradient, but requires channel and carrier proteins? (No energy)
Passive Transport: Facilitated diffusion.
Larger polar molecules, charged molecules and ions.
140
Active Transport:
Transport against the gradient of molecules that cannot cross the membrane freely. uses ATP.
Large polar molecules, and charged molecules.
Uses special carrier proteins- Pumps.
141
What does a resting membrane potential mean electrochemically?
The cell has reached an electrochemical equilibrium.
142
What does a resting potential of -70 mean regarding the intra and extra cellular regions of a nerve cell?
This is describing membrane potential, when the membrane potential is at -70 mV it means inside the cell is 70 mV less positive than outside the cell. (70-80 is usually at rest)
143
What happens when order is increased within the cell?
Heat is generated, this dissipates outside the cell and leads to more disorder outside the cell.
144
What is free energy?
The capacity to do work.
145
Negative change in free energy?
-∆G = spontaneous.
Going down in it's energy state.
146
Endergonic RXN?
Consumes energy
+∆G- non-spontaneous.
147
What kind of energy state change is a condensation RXN?
+∆G, non-spontaneous.
148
What kind of energy state change is a hydrolysis RXN?
-∆G, spontaneous.
149
What is entropy?
The measure of disorder in a system. breaking down (hydrolysis) increases entropy.
150
The breakdown of complex molecules:
Catabolism
151
The synthesis of complex molecules:
Anabolism.
152
What is Oxidation?
OIL: loss of E- release energy -∆G.
153
What is Reduction?
RIG: gain of E- requires energy +∆G.
(appears to gain H)
154
What always happens in oxidative reactions?
Reduction, redox. When something is losing E-, something must gain. always coupled together.
(appears to lose H)
