Biology Flashcards
(145 cards)
1
Q
Nucleoid Region
A
DNA region in prokaryotes
2
Q
Nucleolus
A
Makes ribosomes. Sits in nucleus, no membrane
3
Q
Smooth ER
A
Detox & make lipids
4
Q
Plasmids
A
prokaryotes. Carry DNA not necessary for survival
5
Q
Bacteria Regarding Oxygen Resistance
A
- Obligate Aerobe: Requires O2.
- Obligate Anaerobe: Dies in O2.
- Facultative Anaerobe: Toggle between Aerobic / Anaerobic.
- Aerotolerant Anaerobe: Does not use O2 but tolerates it.
6
Q
Bacteria Gram Purple + Gram Pink
A
- Gram + is PURPLE, THICK peptidoglycan/lipoteichoic acid cell wall.
- Gram – is PINK-RED, THIN peptidoglycan cell wall & an outer membrane.
7
Q
Virulence factor
A
traits that increase how pathogenic a bacterium is such as toxin production, projections that allow bacterium to attach to certain kinds of cells, or evasion of the host’s immune system
8
Q
Prions
A
Infectious proteins. Trigger misfolding. a-helical turns to
b-pleated sheets. decreases Solubility.
9
Q
Viroid
A
plant pathogen
10
Q
Microfilaments
A
Microfilaments assist with cell movement and are made of a protein called actin. Actin works with another protein called myosin to produce muscle movements, cell division, and cytoplasmic streaming. Microfilaments keep organelles in place within the cell.
11
Q
Microtubules
A
Microtubules are filamentous intracellular structures that are responsible for various kinds of movements in all eukaryotic cells. Microtubules are involved in nucleic and cell division, organization of intracellular structure, and intracellular transport, as well as ciliary and flagellar motility.
12
Q
Intermediate filaments
A
Their functions are primarily mechanical and, as a class, intermediate filaments are less dynamic than actin filaments or microtubules. Intermediate filaments commonly work in tandem with microtubules, providing strength and support for the fragile tubulin structures.
13
Q
Epithelia Tissue
A
- the thin tissue forming the outer layer of a body’s surface and lining the alimentary canal and other hollow structures.
- Parenchyma (functional tissue parts of organ).
- Simple: One layer.
- Stratified: Multiple layers.
- Pseudostratified: One layer (looks mult, but really just 1).
- Cuboidal: Cube shape.
- Columnar: Long and narrow.
- Squamous: Flat, scale-like.
14
Q
Connective Tissue
A
Stroma (support, extracellular matrix). Bone, cartilage, tendon, blood.
15
Q
Transformation
A
Gets genetic info from environment.
16
Q
Conjugation
A
Transfer of genetic info via conjugation bridge.
17
Q
Transduction
A
Transfer of genetic info using bacteriophage (virus)
18
Q
Transposons
A
Genetic info that can insert/remove themselves
19
Q
Retrovirus
A
Single stranded RNA. Reverse transcriptase needed to make DNA
20
Q
Lytic vs Lysogenic
A
Lytic- fast: virions duplicate and a bunch made until the cell lyses (breaks down)
Lysogenic: virus integrates into genome as provirus or prophage; goes dormant until stress activates it
21
Q
Cell Cycle
A
G1: Make mRNA and proteins to prep for mitosis
G0: A cell will enter G0 if it DOES NOT need to divide
G1 Checkpoint: Cell decides if it should divide. P53 in charge
S: DNA replicated
G2: Cell growth. Make organelles
G2 Checkpoint: Check cell size & organelles
M: Mitosis and cytokinesis
22
Q
Rb
A
a protein that acts as a tumor suppressor
23
Q
Positive and Negative Growth Signal for Cells
A
Positive Growth Signals:
1) CDK + Cyclin create a complex
2) Phosphorylate Rb to Rb + P
3) Rb changes shape, releases E2F
4) Cell division continues
Negative Growth Signals:
1) CDK inhibitors block phosphorylation of Rb
2) So, E2F stays attached
3) Cell cycle halts
24
Q
SRY gene
A
responsible for the initiation of male sex determination in therian mammals
25
X-Linked Disorders
Males express, females can be carriers
26
Semen consists of what 2 elements:
Sperm + seminal fluid
27
Bulbourethral Glands
Makes viscous fluid to clean out urethra.
28
Sperm Pathway
| SEVE(n) UP
1. Seminiferous tubules: Site of spermatogenesis. Nourished by Sertoli Cells.
2. Epididymis: Stores sperm. Sperm gain motility.
3. Vans deferens: Raise / lower testes.
4. Ejaculatory duct
6. Urethra
7. Penis
29
Nondisjunction
When sister chromatids don’t separate properly during anaphase. Results in aneuploidy; law of segregation also happens in anaphase 1
30
Aneuploidy
the presence of an abnormal number of chromosomes in a cell; a cell with any number of complete chromosome sets is called a euploid cell.
31
Crossing occurs where in Meiosis?
Prophase 1
32
Product of Telophase 1 of Meiosis vs Produce of Telophase 2
forms two haploid daughter cells of unequal sizes
vs.
forms four haploid daughter cells
33
In meiosis, at what phase are chromatids called chromosomes?
Anaphase II
34
Ovaries
Have follicles that produce ova. Controlled by FSH and LH
35
Oogenesis
Production of female gametes
36
Estrogen
Response to FSH. Develops rep tract, thickens uterine wall.
37
Progesterone
Response to LH. Maintains / protects endometrium. “Estrogen establishes; progesterone protects the endometrium”.
38
Female Reproductive Pathway
Egg - peritoneal sac -fallopian tube / oviduct
39
FSH
Follicle Stimulating Hormone.
Males: Triggers spermatogenesis, stimulates Sertoli Cells.
Females: Stimulates development of ovarian follicles.
40
LH
Luteinizing Hormone.
Males: Causes interstitial cells to make testosterone.
Females: Initiates ovulation.
41
Three Types of Stem Cells
- Totipotent: “Total”, can be any type of cell
- Pluripotent: Can be any cell except those found in placental structures
- Multipotent: More specialized. Can be multiple types of cells (adult stem cells)
42
Cell Specialization
Determination: Cell commits to becoming a certain type of cell
Differentiation: Follows determination. Selectively transcribe genes appropriate for cell’s specific function
43
Induction
Group of cells influence the fate of nearby cells. Mediated by inducers, which are commonly growth factors.
44
Summations
Temporal: Same space / Different time
Spatial: Different space / Same time
45
Neurotransmitter removed
| from synaptic cleft via either:
* Breakdown by enzymes
* Reuptake
* Diffusion out of cleft
46
Astrocytes
Blood-brain barrier. Controls solutes moving from bloodstream to nervous tissue.
47
Ependymal Cells
The barrier between cerebrospinal fluid and
| interstitial fluid of the CNS.
48
Microglia
Digest waste in CNS
49
Reflex Arcs
Monosynaptic: Sensory neuron - motor neuron
Polysynaptic: Sensory - interneuron - motor
50
Peristalsis
the involuntary constriction and relaxation of the muscles; lower in sympathetic and higher levels in para
51
Peptide Hormones
```
Made of amino acids
1) Cleaved from larger polypeptide
2) Golgi modifies & activates hormone
3) Put in vesicles released via exocytosis
4) Polar – cannot pass through membrane, so uses
extracellular receptor like GPCR
Common 2nd messengers: cAMP, Ca2+, IP3
Ex: Insulin
```
52
Steroid Hormones
• Made in Gonads & Adrenal Cortex, from Cholesterol
• Don’t dissolve, must be carried by proteins
• Non-polar, so CAN pass through membrane
• They activate nuclear receptors
• Direct action on DNA
Ex: Estrogen / Testosterone / Cortisol
53
Amino Acid Derivative Hormones
Share traits from both peptide & steroid hormones
| Ex: Catecholamines use GPCR, Thyroxine bind intracellularly
54
Direct vs Tropic Hormones
Direct Hormones: Act directly on target tissue/organ. Ex: Insulin.
Tropic Hormones: Require an intermediary. They only affect other
endocrine tissues. Ex: GnRH and LH are both tropic.
55
Diabetes
Type 1: No insulin, so glucose is not able to enter cells.
| Type 2: Desensitized insulin receptors. Glucose unable to enter cells.
56
Air Pathway
- Nares of nose: Nostrils
- Pharynx: Food / air travels through. Air is warmed /
humidified. Vibrissae filter
- Larynx: Air ONLY. Epiglottis covering. Contains vocal cords
- Trachea: Ciliated epithelium collect debris
- Bronchi: Ciliated epithelium collect debris
- Bronchioles: The smallest of the branches of the bronchi
- Alveoli: Sacs where diffusion occurs. Surfactant
REDUCES surface tension. Prevents collapse
Lungs to Heart: pulmonary veins bring + O2
Heart to Lungs: Pulmonary Artery brings - O2
57
Spirometer
Measures lung capacity; CAN NOT measure TOTAL volume
58
Inhalation vs Exhalation
- Inhalation: Negative pressure breathing; Active process; Diaphragm & External Intercostal muscles contract; increased intrapleural space, thoracic cavity, decrease pressure, increase lung volume, decrease lung pressure; Air rushes in
- Exhalation: Passive process, muscles relaxed, decrease in lung volume, increased lung pressure, air leaves lungs, and active exhalation: Internal intercostal & abdominal muscles help
force air out
59
Lysozymes
In nasal cavity/saliva. Attack Gram + peptidoglycan
60
Mast Cells
Antibiotics on surface. Inflammation. Allergic reactions
61
Electric Conduction
the movement of electrically charged particles through a transmission medium.
SA Node- AV Node- Bundle of His- Purkinje Fibers
62
Antigens
Surface proteins on RBCs
63
Rh Factor
- a specific type of antigen
| - Rh+ is dominant. An Rh- person will only create anti-Rh antibodies after exposure to Rh+ blood
64
Coagulation
When the endothelial lining of a blood vessel is damaged, the collagen and tissue factor underlying the endothelial cells are exposed.
Clots are broken down by Plasmin
65
Vasculature
- Arteries: Thick, increase muscular, elastic, allows for recoil and helps propel blood forward.
- Arterioles: Small muscular arteries.
- Capillaries: 1 cell thick endothelial wall, easy diffusion of gases (O2 CO2) and waste (NH3, urea).
- Veins: THIN wall, inelastic. May stretch to accommodate lots of blood, but do not have recoil. Surrounding muscles help pump blood through. Contain valves.
- Venules: Small veins
66
Blood is considered as what kind of tissue?
connective
67
Erythrocytes (RBCs)
Formed in bone marrow. No nucleus, mitochondria, or organelles. Contain Hemoglobin to carry O2.
68
Hematocrit
% of blood composed of RBCs
69
Leukocytes (WBCs)
Hep with Immune system. Formed in bone marrow.
- Granulocytes: Neutrophils, eosinophils, and basophils = nonspecific immunity, inflammatory reactions
- Agranulocytes: Lymphocytes = specific immunity, monocytes digest foreign matter (if monocytes leave bloodstream for organ they are called macrophages)
70
Thrombocytes (Platelets)
Cell fragments. Coagulation
71
Hydrostatic Pressure
Moves fluid out of the blood vessel and into
| the interstitial fluid around it
72
Osmotic Pressure
“Sucking” pressure generated by solutes as
| they draw H2O into the bloodstream.
73
Oxygen vs CO2
Oxygen: Carried by hemoglobin.
CO2: Some carried by hemoglobin, most exist in the bloodstream as bicarbonate HCO3
74
Innate Immunity
Defenses that are always active but NON- SPECIFIC. Skin, mucus, stomach acid, tears etc.
75
Adaptive Immunity
Defenses that take time to activate and are SPECIFIC to the invader.
76
Non-cellular Innate Immunity Defenses
- Skin
- Mucus
- Lysozymes
- Complement System: Can punch holes in the cell walls of bacteria making them osmotically unstable, leading to lysis. Also triggers opsonization.
- Interferons: Given off by virally infected cells. Interfere with viral replication and dispersion
77
Cellular Innate Immunity Defenses
- Macrophages: Ingest pathogens and present them on MHC-II. Secrete Cytokines
- MHC-I: Present in all nucleated cells. Displays endogenous antigen to cytotoxic CD8+ T-cells.
- MHC-II: Present in professional antigen-presenting cells (macrophages, dendritic cells, some B-cells, and certain activated epithelial cells). Displays exogenous antigen to helper CD4+ T-Cells.
- Dendritic Cells: Antigen-presenting cells in the skin
- Natural Killer Cells: Attack cells low on MHC, including virally infected cells and cancer cells
- Granulocytes: (Neutrophils) Activated by bacteria, conduct phagocytosis. (Eosinophil) Activated by parasites & allergens histamines (Basophils:) Activated by allergens, inhibit blood clotting.
78
```
Humoral Immunity ( 1 of 2 Adaptive Immune System)- Centers on antibody production by B-Cells. Kills
antigens while they are floating around in the fluid (humor).
```
- B-Lymphocytes (B-cells): Made and mature in bone marrow. Activated in spleen or lymph nodes. Express antibodies on its cell surface.
- Antibodies (Ig): Produced by plasma cells, which are activated B-Cells. Target an antigen. Contain 2 heavy chains and 2 light chains. Constant region & variable region. Tip of variable region is the antigen binding region.
- Hypermutation: Mutation of the antigen binding site on an antibody. Results in varying affinities of antibodies for a specific microbe. 5 diff isotypes (IgM, IgD, IgG, IgE, IgA)
- Opsonization: Antibodies mark pathogens for destruction.
- Agglutination: Pathogens clump together into insoluble complexes. Caused by opsonizing pathogens.
- Memory B-Cells: Lie in wait for a second exposure to pathogen. Secondary response is more rapid and vigorous.
79
Cell- Mediated (Cytotoxic) Adaptive Immunity System: Centers on T-Cells. Responds to cells
once they have been infected by the antigen.
- T-Lymphocytes (T-cells): Made in bone marrow, mature in Thymus. Coordinate immune system and directly kill infected cells. Cell- mediated immunity.
- Positive/Negative Selection: Maturation of T-Cells. Facilitated by thymosin. Occurs in Thymus. (Positive (Selection) Mature only T-cells that can respond to the presentation of antigen on MHC. (Negative Selection) Causes apoptosis in T-cells that are self-reactive
- Helper T-Cells: Th or CD4+. Respond to antigen on MHC-II. Coordinate rest of the immune system, secreting lymphokines to activate immune defense. (Th1) secrete interferon gamma (Th2) activate B-Cells, in parasitic infections
- Cytotoxic T-cells: Tc, CTL, or CD8+. “Killer cells”. Respond to antigen on MCH-I and kill virally infected cells
- Suppressor T-Cells: Treg. Down regulate the immune response after an infection and promote self-tolerance. Defective suppressor T-Cells lead to autoimmune conditions.
- Memory T-Cells: Serve a similar function to memory B-Cells
- Autoimmune Conditions: A self-antigen is recognized as foreign, and the immune system attacks normal cells
- Allergic Reactions: Nonthreatening exposures incite an inflammatory response
- Immunization: Induces active immunity (activation of B-Cells that produce antibodes)
- Passive Immunity: Transfer of antibodies to an individual. Breast milk.
80
Lymphatic System
• Circulatory system that consists of one-way vessels with intermittent lymph nodes
• Provides for mounting immune responses
• Connects to the cardiovascular system via the thoracic duct in the
posterior chest
• Equalizes fluid distribution, transports fats and fat-soluble compounds in chylomicrons
• Edema results when the lymphatic system is overwhelmed and can’t drain excess fluid from tissues
81
Intracellular Digestion
The oxidation of glucose and fatty acids to make energy.
82
Extracellular Digestion
Process by which nutrients are obtained from food. Occurs in alimentary canal.
83
Mechanical Digestion
Physical breakdown of large food molecules into smaller particles.
84
Chemical Digestion
The enzymatic cleavage of chemical bonds such as the peptide bonds of proteins or the glycosidic bonds of starches.
85
Peristalsis
Rhythmic contractions of the gut tube. Increase in parasympathetic nervous system and decrease in sympathetic nervous system
86
Mastication
chewing
87
Oral Cavity
Mastication starts the mechanical digestion. Salivary
amylase and lipase start the chemical digestion of food.
Food is formed into a bolus and swallowed.
88
Pharynx
Connects the mouth to the esophagus. The epiglottis
| prevents food from entering the larynx.
89
Esophagus
Propels food to the stomach using peristalsis. Top third has skeletal muscle and is under somatic control. Bottom third has smooth muscle, middle third has combo of both. The middle & bottom are under autonomic control.
90
Stomach
An acidic (pH = 2) environment. Four parts: fundus, body, antrum and pylorus. The enzyme pepsin chemically breaks down proteins.
91
Secretory cells that line the Stomach
- Mucous Cells: Produce bicarbonate-rich mucus to protect stomach wall from acid.
- Chief Cells: Secrete pepsinogen, a protease activated by the acidic environment.
- Parietal Cells: Secrete HCl and intrinsic factor, which is needed for vitamin B12 absorption.
- G-Cells: Secrete gastrin, a peptide hormone that HCl
secretion & gastric motility.
92
Chyme
After processing in the stomach, food particles are now called chyme. Chyme exits through pyloric sphincter - duodenum.
93
Duodenum
First part of small intestine. A basic (pH = 8.5) environment. Site of the majority of chemical digestion.
94
Enzymes in Duodenum
- Disaccharidases: Brush-border enzymes that break down maltose, isomaltose, lactose, and sucrose into monosaccharides.
- Aminopeptidase + Dipeptidase: Brush-border peptidases.
- Enteropeptidase: Activates trypsinogen and procarboxypeptidases.
95
Hormones in Duodenum
- Secretin: Peptide hormone. Stimulates release of pancreatic juices and slows motility.
- Cholecystokinin: Stimulates bile release from gallbladder, release of pancreatic juices, and satiety.
96
Absorption and Defecation
- The jejunum and ileum of the small intestine are primarily involved in absorption. The small intestine is lined with villi, which are covered with
microvilli.
- Villi: (Capillary Bed) Absorbs water-soluble nutrients.
(Lacteal) Absorbs fat, sends to lymphatic system.
- Vitamin Absorption: (Fat-Soluble) Only A,D,E,K; enter lacteal. (Water-Soluble) All others; enter plasma directly.
- Large Intestine – absorbs H2O and salts, forms feces (Cecum) Outpocketing that accepts fluid from small
intestine through ileocecal valve. Site of attachment of the appendix. (Structure of Colon) Ascending / transverse / descending / sigmoid (Gut Bacteria) Produce vitamin K and biotin (vitamin B7).
97
Pancreas
Acinar Cells produce pancreatic juices that contain
| bicarbonate, pancreatic amylase, pancreatic peptidases, and pancreatic lipase.
98
Liver
Synthesizes bile, albumin and clotting factors. Process
nutrients. Detox: NH3 - Urea, as well as alcohol & drugs.
Liver receives blood from the abdominal portion of
digestive tract via Hepatic Portal Vein.
99
Gallbladder
Stores & concentrates bile. CCK stimulates bile release into biliary tree, which merges with pancreatic duct.
100
Kidney
Contains a cortex and medulla. Produces urine which dumps into the ureter at the renal pelvis. Urine is then collected in the bladder until it is excreted through the
urethra; nephron is the functional unit
101
Renal Portal System
Two capillary beds in series (glomeruli & nephron). Blood
flow: renal artery - afferent arterioles - glomeruli -
efferent arteriole - vasa recta, which surround nephron -
renal vein.
102
Filtration
Bowman’s capsule moves solutes from blood - filtrate.
Direction and rate determined by hydrostatic and oncotic
pressure differentials between the glomerulus and
Bowman’s space.
103
Secretion
The movement of solutes from blood - filtrate anywhere
| other than Bowman’s capsule.
104
Reabsorption
The movement of solutes from filtrate - blood.
105
Aldosterone
Steroid hormone synthesized in Adrenal Cortex in response to Angiotensin 2 or high [K+]. It is derived from cholesterol. Increases Na+ reabsorption in the distal convoluted tubule and collecting duct, thereby increasing H2O reabsorption. Result: increase BP but no change in blood osmolarity
106
ADH (Vasopressin)
Peptide hormone synthesized by hypothalamus and
released by posterior pituitary. Increase permeability of the collecting duct to H2O, which increases H2O reabsorption. Result: increase BP and decrease blood osmolarity, concentrated urine.
107
Bladder
- Detrusor Muscle: Muscular lining of bladder. Parasympathetic control
- Internal Urethral Sphincter: Smooth muscle. Parasympathetic control
- External Urethral Sphincter: Skeletal muscle. Voluntary control
108
Nephron
- Proximal Convoluted Tubule (PCT): Site of bulk reabsorption of glucose, amino acids, soluble vitamins, salt, and H2O. Site of secretion for H+, K+, NH3, and urea
- Descending Limb of the Loop of Henle: Permeable to H2O but NOT salt; therefore, as the filtrate moves into the more osmotically concentrated renal medulla, water is reabsorbed from the filtrate.
- Countercurrent Multiplier System: The vasa recta and nephron flow in opposite directions, creating a countercurrent multiplier system that allows maximal reabsorption of water
- Ascending Limb of the Loop of Henle: Permeable to salt but NOT to H2O; therefore, salt is reabsorbed both passively and actively. The diluting segment is in the outer medulla; because salt is actively reabsorbed in this site, the filtrate becomes hypotonic compared to the blood
- Distal Convoluted Tubule (DCT): Responsive to aldosterone and is a site of salt reabsorption and waste product excretion, like the PCT.
- Collecting Duct: Responsive to both aldosterone and ADH. Has variable permeability, which allows reabsorption of the right amount of H2O depending on the body’s needs.
109
Skin Layers
Epidermis / Dermis / Hypodermis (subcutaneous layer)
110
Epidermis
- Stratum Basale: Stem cells to keratinocytes
- Stratum Spinosum: Lagerhans cells
- Stratum Granulosum: Keratinocytes die
- Stratum Luciderm: Only on thick, hairless skin
- Stratum Corneum: Mult thin layers, flat keratinocytes
111
Langerhans Cells
Macrophages that are antigen-presenting cells in skin
112
Melanin
Produced by Melanocytes. Protects skin from DNA damage caused by ultraviolet radiation
113
Dermis
Papillary layer and reticular layer. Sensory:
- Merkel Cells: Deep pressure & texture
- Free Nerve Endings: Pain
- Meissner’s Corpuscles: Light touch
- Ruffini Endings: Stretch
- Pacinian Corpuscles: Deep pressure & vibration
114
Hypodermis
Fat and connective tissue. Connects skin to body
115
Thermoregulation
- Sweating: Evaporative cooling
- Piloerection: Warming
- Shivering: Warming
- Vasodilation / Vasoconstriction: Cool / warm
116
Skeletal Muscle
• Support & movement, blood propulsion, thermoregulation, striated
• Voluntary (somatic) control
• Multinucelated
- Red Fibers: Slow twitch. Support (dark meat). Carry out oxidative phosphorylation.
- White Fibers: Fast-twitch. Active (white meat). Anaerobic metabolism.
117
Smooth Muscle
* Respiratory, reproductive, cardiovascular, digestive
* Involuntary (autonomic) control
* Uninucleated
* Can display myogenic activity without neural input
118
Cardiac Muscle
* Contractile tissue of the heart
* Involuntary (autonomic) control
* Uninucleated (sometimes binucleated)
* Can display myogenic activity
* Cells connected with intercalated discs that contain gap junctions
119
Types of Bone
- Compact Bone: Strength and density.
- Spongy Bone: (cancellous)
Lattice-like structure of bony spicules known as trabeculae.
Cavities filled with bone marrow.
- Bone Marrow: (Red) Filled with hematopoietic stem cells.
(Yellow) Fat
- Long Bones: Shafts called diaphysis that flare to form metaphyses and that terminate in epiphyses. Epiphyses contain epiphyseal (growth) plate.
120
Periosteum
Connective tissue that surrounds bone.
121
Ligaments
Attach bones to other bones.
122
Tendon
Attach bones to muscles.
123
Bone Matrix
Osteons are the chief structural unit of compact bone
124
Bone Remodeling
- Osteoblasts build bone, osteoclasts resorb bone.
- Parathyroid Hormone and Vitamin D: increase resorption of bone and [blood Ca2+].
- Calcitonin: increase bone formation and decrease [Ca2+] in blood.
125
Synovial Fluid
Secreted by synovium, lubricates joints.
126
Fetus Skeletal System
Bones form from cartilage through endochondroal
| ossification. Skull bones form directly from mesenchyme in intramembranous ossification.
127
Sarcomeres
• Basic contractile unit of striated muscle
• THICK myosin and THIN actin filaments
• Troponin & tropomyosin found on the thin filament and regulate actin- myosin interactions
o Z-lines: Define the boundary of each sarcomere
o M-line: Middle of sarcomere
o I-band: Only actin filaments.
o H-zone: Only myosin filaments.
o A-band: Contains both actin and myosin. Only part that
maintains a constant size during contraction.
• Sarcomeres attach end-to-end to become myofibrils. Each myocyte contains many myofibrils
- Sarcoplasmic Reticulum: Ca2+ filled modified endoplasmic reticulum.
- Sarcolemma: Cell membrane of a myocyte.
- T-tubules: Connected to sarcolemma. Carry signals.
128
Contraction and Relaxation
* Begins at neuromuscular junction, where the efferent neuron release acetylcholine that binds to receptors on the sarcolemma, causing depolarization
* Depolarization spreads down sarcolemma to T-tubules, triggering the release of Ca2+
* Ca2+ binds to troponin, causing a shift in tropomyosin and exposure of the myosin-binding sites on the actin filament
* Shortening of the sarcomere occurs as myosin heads bind to the exposed sites on actin, forming cross bridges and pulling the actin filament along the thick filament. “Sliding filament model”
* Muscles relax when acetylcholine is degraded by acetylcholinesterase, terminating the signal and allowing Ca2+ to return to the SR.
* ATP binds to myosin head, allowing it to release form actin
129
Simple Twitch
Single muscle fiber responds to brief stimulus.
130
Frequency Summation
Addition of multiple simple twitches before the muscle has a chance to fully relax.
131
Oxygen Debt
Difference between O2 needed and O2 present.
132
Myoglobin
Heme-containing protein that is a muscular oxygen reserve.
133
Penetrance
he proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also express an associated trait (the phenotype)
134
Genetic Leakage
Flow of genes between species via hybrid offspring.
135
Taxonomic Rank
Kingdom, phylum, class, order, family, genus, species.
| “King Phillip Came Over From Great Spain”
136
Law of Segregation
An organism has two alleles for each gene, which segregate during Anaphase I. Because of this, gametes carry only one allele for a trait.
137
Law of Independent Assortment
The inheritance of one allele does not influence the probability of inheriting a given allele for a different trait (except for linked genes).
138
Nucleotide Mutation
- Point Mutations: The substituting of one nucleotide for another.
- Frameshift Mutations: Moving the 3 letter reading frame.
Results:
- Silent: No effect on the protein.
- Missense: Replace one amino acid with another.
- Nonsense: A stop codon replaces an amino acid.
- Insertion/Deletion: Shift in the reading frame, leading to a change in all downstream amino acids.
139
Chromosomal Mutations - affects whole segment of DNA
- Deletion: A large segment of DNA is lost.
- Duplication: A segment of DNA is copied multiple times.
- Inversion: A segment of DNA is reversed.
- Insertion: A segment of DNA is moved from one
chromosome to another.
- Translocation: A segment of DNA is swapped with a segment of DNA from another chromosome.
140
Recombination Frequency
The likelihood of two alleles being separated during crossing over in meiosis. Farther = increased likely
141
Modern Synthesis Model
Neo-Darwinism. Mutation and recombination are
| mechanisms of variation. Differential reproduction.
142
Inclusive Fitness
If a population meets certain criteria, then the allele frequencies will remain constant.
143
Punctuated Equilibrium
Considers evolution to be a very slow process with
| intermittent rapid bursts of evolutionary activity.
144
Mode of Natural Selection
- Stabilizing Selection: Keeps phenotypes in a narrow range, excluding extremes.
- Directional Selection: Moves the average phenotype toward an extreme.
- Disruptive Selection: Moves toward two different phenotypes at the extremes, can lead to speciation.
- Adaptive Radiation: Rapid emergence of multiple species from a common ancestor, each has a niche.
145
Molecular Clock Model
The degree of difference in the genome between
two species is related to the amount of time since
the two species broke off from a common ancestor.
