Cell Biology Flashcards
1
Q
What is the cell theory?
A
- Cells are the smallest independent units of life
- All living things are made up of cells
- Cells are formed by the reproduction of existing cells
2
Q
Life on earth is what?
A
Carbon-based
3
Q
What is an element?
A
A chemically pure substance that cannot be broken down
4
Q
What are covalent bonds?
A
When electron pairs are shared, very strong
5
Q
What is a valence shell?
A
The outer layer of the atom
6
Q
What is electronegativity?
A
The attractive force that an atom exerts on electrons
7
Q
How do ionic bonds form?
A
By chemical attraction of opposite charges
- The more electronegative atom steals an electron
8
Q
What kind of bond does solid, water, liquid, and gas have?
A
Hydrogen bonds (sharing of an H atom)
9
Q
Polar molecules are:
A
Hydrophilic (water-loving)
10
Q
Non-polar molecules are:
A
Hydrophobic (water-hating)
11
Q
What is hydrophilic interaction?
A
Attraction, polar to polar
12
Q
What is hydrophobic interaction?
A
Attraction, non-polar to non-polar
13
Q
What ions do acids release?
A
H+
14
Q
What ions do bases release and accept?
A
Accepts H+ and releases OH-
15
Q
What is carbon?
A
A “tinkertoy” atom
- Incredibly flexible- used to build many types of complex macro molecules
16
Q
What is a common theme between living systems?
A
Many are biological polymers with repeated subunits
17
Q
What is a polymer?
A
A repeating unit (more than two)
18
Q
What are carbohydrates?
A
A source of energy
- Basic unit: CH2O
- Ex: glucose (disaccharides)
19
Q
What are polysaccharides?
A
Form rigid biological structures (ex: cellulose + chitin)
20
Q
What are the 3 classes of amino acids?
A
Electrically charged, polar, non-polar
21
Q
What is the shape of a protein?
A
A folded polypeptide
22
Q
What is the structure of a non-polar amino acid?
A
Amino acids have a hydrocarbon side-chain (ex: CH3)
23
Q
What is the structure of a polar amino acid?
A
Amino acids have side chains with partial charge (polar uncharged), or net (+) charge, or net (-) charge
24
Q
What are lipids?
A
Fats, steroids, phospholipids
25
What is fat?
Simple 3-carbon lipid
| - Fatty acid tails, hydrophobic
26
What is a phospholipid?
2 fatty acid tails (hydrophobic) and charged phosphate head (hydrophilic)
27
What is a steroid?
Composed of carbon rings (5 or 6 carbons per ring)
- Cholesterol, estrogen, testosterone (hormones)
- Cell membranes (animals only)
28
What are the 4 bases of nucleic acids?
A (adenine), G (guanine) --- Purines
| T (thymine), C (cytosine) --- Pyrimidines
29
What are the subunits of a nucleotide?
1 of 4 bases + a phosphate + a sugar
30
What is DNA?
A double helix (two strands linked together that are identical)
- bonded by hydrogen bonds
31
What is the structure of DNA?
- Anti-parallel strands of repeating subunits
- Backbone (phosphate and sugar) --- covalent bonds
- Rungs: A/G ::: T/C (hydrogen bonds)
32
What does the 1st law of dynamics state?
That energy cannot be created or destroyed
33
What are the types of energy?
- Kinetic potential: mass, gravity, speed
- Chemical: e.g. chemical bonds, ATP
- Radiant: e.g. sunlight, photosynthesis
- Thermal e.g. sunlight, thermal regulation
34
What is energy transfer?
Described as work and heat
35
What is a calorie?
* Unit of energy represented on food labels
* Calories are consumed by cells to do work
* Extra calories can be stored as fat
36
What is the basal metabolic rate (BMR)?
Represents the resting energy of an awake, resting but alert person
- 70 Calories/hour or 1680 Calories/day
37
What is metabolism?
All chemical reactions occurring in the body
38
What is metabolic rate?
The rate at which the body uses energy
| - Influenced by: body weight, sex, exercise, genetic makeup, age and nutritional status
39
What are enzymes?
Proteins that catalyze chemical reactions in the cell
•They work by lowering the activation energy needed for a reaction
•They lower the energy barrier required for a reaction
•They are very specific
•They speed up the rate of reaction (or product production) by reducing the energy needed for the reaction to occur
•Enzymes DO NOT create reactions that create reactions that would not occur in their absence
•If enzymes have more energy or are present, the energy barrier is lower
40
What is cellular respiration?
A series of chemical reactions that convert energy from food into chemical reactions that convert energy from food into chemical energy in ATP
41
What does ATP consist of?
Adenine, a sugar, and 3 phosphate groups
| - it can power different kinds of work in the cell
42
What happens when a phosphate group is transferred from ATP to another molecule?
Energy is transferred and ADP is produced
43
What are prokaryotic cells?
* Generally small (1/10 the size of a small eukaryotic cell)
* No nucleus
* Few internal membranes
* Never multicellular, but can form colonies
* Cell wall made of peptidoglycan - sugars and peptides (ex: bacterial cell)
* Some are aerobic (use oxygen) or anaerobic (don’t use oxygen)
44
What are eukaryotic cells?
* Larger than bacteria
* Has a nucleus
* Many internal membranes
* Membrane-based organelles
* Unicellular or multicellular
* Cell walls- depends on kingdom
* All are aerobic (use oxygen)
45
What is the nucleus?
Contains cells' DNA
46
What is the nucleolus?
more specialised part of the nucleus in the middle
47
What is the centriole?
involved in the development in spindle fibers (only in animal cells)
48
What are ribosomes?
Bind messenger RNA and transfer to synthesize polypeptides and proteins
49
What is the cytoskeleton?
Gives the cell structure
50
What is the plasma membrane?
separates interior of cell from outside of cell
51
What is the lysosome?
Contains degrading enzymes
52
What is the mitochondria?
The powerhouse of the cell
53
What is the rough endoplasmic reticulum?
Produces proteins
54
What is the Golgi apparatus?
involved in secretion and intracellular transport
55
What is cytosol?
intracellular fluid
56
What is the smooth endoplasmic reticulum?
Makes lipids and hormones
57
What are membranes?
Semi-permeable, adapted to allow different things to go in and out
58
What are phospholipids?
- Have polar and hydrophobic properties
- Charged phosphate head and hydrophobic tails
• As a result, there is a phospholipid bilayer
59
Does diffusion require ATP?
No
60
What is osmosis?
- Water across a membrane
- No ATP required
- The water molecules move from high to low concentration
- More water = less salt
- In the case of plants, when water moves out the cell wall maintains shape/size but the cell lacks turgor
61
When do you use ATP for transport?
For the transport of a solute across a membrane against a concentration gradient
62
What is active transport?
Moving molecules from low to high concentration requires energy and a channel
- Moves molecules in bulk or particles too large for passive/facilitated diffusion
63
What is endocytosis?
Moving into cell
64
What is exocytosis?
Moving out of cell
65
As ATP is used, what happens to ADP?
It accumulates
66
What is aerobic cellular respiration?
cellular respiration that requires oxygen
67
What are the 3 steps of aerobic cellular respiration?
1. Glycolysis (in the cytoplasm)
2. Citric acid cycle (in the mitochondria)
3. Electron transport chain (in the mitochondria)
68
What is glycolysis?
- A 6-carbon glucose molecule is broken down into two 3 carbon pyruvic acid molecules (final product)
- Glycolysis takes place in the cytosol
- Produces 4 ATP molecules in total, 2 ATP molecules (net) and NADH
- NAD+ is used as a chemical taxicab
- NAD+ molecules pick up electrons, via hydrogen ions released during glycolysis, producing NADH
69
What is the citric acid cycle?
- Starts with pyruvic acid (the end of product glycolysis) it HAS to be transported to the mitochondria, specifically the matrix
- Series of chemical reactions catalyzed by 8 different enzymes in the mitochondrial matrix
- The result is the generation of 2 ATP molecules, the release of carbon dioxide and the electron carriers NADH and FADH2
70
What is the electron transport chain?
- H+ ions pass through protein channels called ATP synthase, generating 32 or 34 ATP molecules as they do
- At the end of the chain, the two H atoms (electrons) combine with oxygen to produce water
- H+ ions are charged, and unlikely to diffuse across the membrane
71
What can be used to make ATP when carbohydrates are unavailable?
Proteins and fats
72
What is fermentation?
ATP synthesis without oxygen
73
What is produced through aerobic respiration?
water and CO2, along with ATP
74
What is body mass index (BMI)?
Correlates amount of body fat with risk of illness and death, using both weight and height
75
What is considered obese?
BMI of 30 or higher
76
What is insulin?
hormone that triggers cells to take up glucose; produced by beta cells of the pancreas
77
What is diabetes?
Disorder of carbohydrate metabolism
78
What is type 1 diabetes?
- not associated with obesity
- Usually arises in childhood
- Cannot produce insulin (no beta cells)
- Treated with daily insulin injections
79
What is type 2 diabetes?
- associated with obesity
- Usually arises in adults
- May be controlled by diet and exercise
80
What is systolic?
Blood pressure as the heart contracts
81
What is diastolic?
Blood pressure while the heart is relaxing
82
What is hypertension?
Blood pressure persistently over 140/90
83
What is a heart attack?
A sudden loss of blood to the heart because of blocked arteries
84
What is a stroke?
A sudden loss of blood to the brain because of blocked arteries
85
What is cholesterol?
A lipid that can build up in arteries
86
What are low-density lipoproteins (LDLs)?
distribute cholesterol throughout the body and dumps excess in the arteries
87
What are high-density lipoproteins (HDLs)?
carry excess cholesterol to the liver for excretion as bile
88
What is anorexia?
Self-starvation
| - Can starve heart muscles, producing altered rhythms
89
What is amenorrhea?
Cessation of menstruation
- Can be permanent and result in sterility
- Increases rick of osteoporosis
90
What is bulimia?
Binge-eating followed by purging
- Many of the same health effects as anorexia
- May lead to stomach rupture
- Dental and gum problems from stomach acid
- Dehydration (sometimes fatal)
91
Why are leaves green?
Wavelengths 530-630 (green) are reflected while other colours are absorbed
92
What is the amino acid form?
Amino group, carboxyl group, side group
93
What is phosphorylation?
When a phosphate group is transferred from ATP to another molecule
94
What is RNA?
• Single-stranded
• Nucleotides comprised of ribose, phosphate, and nitrogenous base
• 4 bases: A, C, G and U (uracil)
• 3 types of RNA are needed to synthesize proteins:
- mRNA
- tRNA (they can form intramolecular H bonds; makes an anticodon)
- rRNA
95
What is a codon?
It specifies each amino acid, comprised of 3 nucleotides = 64 possible combinations
- 61 codons for amino acids
- multiple codons = one amino acid
96
What are genes?
* They encode proteins
* They are a sequence of DNA that contains information to make a protein
* The DNA stores information required to make every protein in the cell
97
What is a promoter?
doesn’t produce protein info, but displays machinery in order to make
98
What is the start codon?
methionine --> ATG (promoter goes in front of this)
99
What are the stop codons?
TAA
100
What is transcription?
- Occurs in the nucleus
- RNA polymerase binds to the promoter region of the gene
- RNA polymerase zips down the length of gene, matching RNA nucleotides with complementary DNA nucleotides, forming messenger RNA (mRNA)
101
What is translation?
o Occurs in the cytoplasm
Requires:
- mRNA (made during transcription)
- amino acids (20 different types)
- transfer RNAs (tRNAs, for each amino acid)
- energy (ATP) to bond an amino acid to a tRNA)
- ribosomes
- a protein is put together one amino acid at a time
-the ribosome attaches to the mRNA at the promoter region (before AUG)
-the ribosome facilitates the docking of tRNA anticodons to mRNA codons, also provides a place for energy transfer
- when two tRNAs are adjacent, a peptide bond is formed between the amino acids
- a chain of amino acids is formed (polypeptide)
102
What is tRNA?
* Transfer RNA carries amino acids and matches its anticodon with codons on mRNA
* Codons are 3 nucleotides long
103
Why is GFP useful?
Because of the fact that the genetic code is universal and can be used for multiple different organisms
- Ex: Alanine codes for bacteria, jelly fish, insects, mammals, etc.
104
What are mutations?
* Changes in genetic sequence
* These changes might affect the order of amino acids
* Protein function is dependent on the precise order of amino acids
105
What are the possible outcomes of mutation?
- No change in protein
- Non-functional protein
- Different protein
106
What is a neutral mutation?
doesn’t change sequence of protein, new codon = same amino acid
107
What is a base-substitution mutation?
substitution of one base for another
| - Can change codon, polypeptide sequence, and protein function (and potentially make it dysfunctional)
108
What is a frameshift mutation?
addition or deletion of a base, which changes the reading frame (sequence of codons)
- Incomplete or different protein
109
What do cells use to regulate gene expression?
Repressors
-they bind to the promoter and prevent the RNA polymerase from binding
Activators
- help the RNA polymerase bid to the promoter
110
What are the regulations past the promoter?
- Regulation by chromosome condensation
- Folding up chromosomes prevents transcription
- Regulation by mRNA degradation
- Nucleases cut mRNA
- Regulation of translation
- Slowing of binding of the mRNA to the ribosome
- Regulation of protein degradation
- Proteases degrade proteins that are malfunctioning
111
What is interphase?
The DNA replicates
112
What is mitosis?
The copied chromosomes are moved into daughter nuclei
- Occurs in somatic or body cells
- Produces cells with identical DNA
113
What is cytokinesis?
the cell is split into 2 daughter cells
| - Lots of things have to be done correctly in order for a cell to successfully divide
114
What are the consequences of lagging chromosomes?
- One cell would lack a chromosome, and one would have too many
- This can cause diseases and growth defects
- Chromosome will lag behind and get damaged in the cleavage furrow
- You’ll end up with a micronucleus that will eventually get destroyed
115
Why are there lagging chromosomes?
- Imbalance in tug-of-war between two ends of spindle
116
What happens if a mistake is detected within a cell?
Normal cells halt at checkpoints and make repairs
| - Cell must pass the survey to proceed with cell division
117
What are the 3 major checkpoints of the cell cycle?
G1, G2 and metaphase
118
What are the 4 stages of mitosis?
- Prophase
- Metaphase (if even one chromosome is wrong, anaphase is delayed)
- Anaphase
- Telophase
119
How do oncogenes cause cancer?
- When proto-oncogenes mutate, they become oncogenes
- Their proteins no longer properly regulate cell division
- They usually overestimate cell division
120
What are the 3 paths to cancer through oncogenes?
* Translocation or transposition (gene moved to new focus, under new controls)
* Amplification (multiple copies of gene)
* Point mutation
121
What are proto-oncogenes?
Genes that code for cell cycle control proteins
122
What are tumour suppressor genes?
Genes for proteins that stop cell division if conditions are not favourable
- When mutated, can allow cells to override checkpoints
123
How do you determine whether a tumour is benign or malignant?
- Depending on the number of mutation and whether the tumour suppressor protein is functional
124
What is the multiple hit model?
Process of cancer development requires multiple mutations
- Some mutations may be inherited (familial risk)
- Most are probably acquired during a person’s lifetime
125
What happens after a loss of contact inhibition?
cells will now pile up on each other
126
What happens after a loss of anchorage dependence?
enables a cancer cell to move to another location
127
What happens when a tumour is immortalized?
cells no longer have a fixed number of cell divisions due to an enzyme called telomerase
128
What is the difference between malignant and benign tumours?
Benign: tumour cells grow only locally and cannot spread by invasion or metastasis
Malignant: cells invade neighboring tissues, enter blood vessels, and metastasize to different sites
129
What is a biomarker?
When some cancers produce increased amount of a characteristic protein (non-functional or altered)
130
What is a biopsy?
surgical removal of cells or fluid for analysis
131
What is a laparascope?
surgical instrument with a light, camera, and small scalpel
132
What is chemotherapy?
Drugs that selectively kill dividing cells
- Combination of different drugs used (“cocktail”)
- Interrupt cell division in different ways
- Helps prevent resistance to the drugs from arising
- Normal dividing cells are also killed (hair follicles, bone marrow, stomach lining)
133
What is radiation therapy?
Use of high-energy particles to destroy cancer cells
- Damages their DNA so they can’t continue to divide or grow
- Usually used on cancers close to the surface
- Typically performed after surgical removal of tumor
- If a person remains cancer free after treatment for 5 years they are in remission and after 10 years they are considered to be cured
134
What is a tardigrade?
• Has 8 legs, also called “water bear” and is almost impossible to kill
• When dehydrated can go more than 10 years without food or water
• When hydrated it:
- Can survive unprotected in space
- Extreme temperatures
- Can withstand vacuum and high pressure
- Can survive ionizing and UV radiation that would kill a human
135
Why are tardigrades so tough?
- Extra copies of genes required to repair DNA
- Loss of genes that stimulate autophagy in the presence of stress
- Tardigrade-specific genes that protect DNA (Dsup)
- Nay tardigrade genes function still unknown
- Can turn into glassy material
136
What are telomeres?
- End caps that protect the chromosomes
| - Animal cells need them to divide
