Biology Flashcards
Blueprint MCAT Prep
What kind of bonds create permanent dipoles in molecules?
Polar Covalent bonds
What is the driving force behind intermolecular forces and physical/chemical compounds of various functional groups?
Polarity
Order these molecules in terms of increasing polarity: Carboxylic Acids, charged molecules, alkanes, alcohols
Alkanes, alcohols, carboxylic acids, charged molecules
What effect can symmetrical polar bonds have on the overal polarity of a molecule?
Symmetrical polar bonds may result in an overal non-polar molecule
What four groups are bound to the central carbon atom in an amino acid?
-NH2, -COOH, -H, -R
What Amino Acids are nonpolar?
Glycine, Alanine, Valine, Isoleucine, Leucine, Methionine, Proline, Phenylalanine, Tyrosine, Tryptophan
What Amino Acids are polar, uncharged?
Serine, Threonine, asparagine, glutamine, Cysteine
What Amino Acids are positively charged/basic?
Arginine, Histidine, Lysine
What Amino Acids are negatively charged/acidic?
Aspartic Acid, Glutamic Acid
Glycine
Alanine
Valine
Leucine
Isoleucine
Methionine
Phenylalanine
Tryptophan
Proline
Serine
Threonine
Cysteine
Tyrosine
Asparagine
Glutamine
Aspartate
Glutamate
Lysine
Arginine
Histidine
Alkanes
Alkenes
Alkynes
Alkyl Halides
Alcohols
Ethers
Thiols
Amines
Imines
Aldehydes
Ketones
Carboxylic Acids
Esters
Lactone (cyclic ester)
Amides
Lactam (cyclic amide)
Thioesters
Anhydrides
Acyl Halides
Pyrrole
Imidazole
Primary Structure of Proteins
Amino Acid Sequence
Secondary Structure of Proteins
H-bonding between amino acid backbone components
Tertiary Structure of Proteins
Side chain interactions
Quaternary Structure of Proteins
Interactions between polypeptides
What kind of molecule is this?
Triglycerol (known for saponification process)
Phospholipid (known for bing major component of lipid bilayer in cell membranes)
Sphingolipid (Generally found on the outside of plasma membrane and play crucial role in signaling)
What are the 3 primary functions of Lipids?
Signaling, Structure, and Energy Storage
What are the primary functions of proteins?
Building blocks of body, structure and signaling
Cholesterol (contributes to fluidity of cell membrane)
Testosterone
Vitamin D
Prostaglandins (Well-known for the regulation of inflammation)
What is the difference between terpenes and terpenoids?
Terpenoids are terpenes that are modified with other organic substituents
Terpenes (made of isoprene units)
What are carbohydrates primarily known for?
Being a major source of energy (used in metabolism)
Glucose
Fructose
Galactose
What monosaccharides make up sucrose (a disaccharide)?
Glucose + Fructose
What monosaccharides make up Lactose?
Glucose + Galactose
What monosaccharides make up Maltose?
Glucose + Glucose
What is Starch?
Polymers of glucose used for energy storage in plants
What is Glycogen?
Polymers of glucose used for energy storage in animals
What are Chargaff’s Rules for DNA and RNA?
DNA: A-T & C-G
RNA: A-U & C-G
Which nitrogenous bases are Purines?
Adenine and Guanine
Which nitrogenous bases are Pyrimidines?
Cytosine, Thymine, and Uracil
Adenine
Guanine
Cytosine
Thymine
Uracil
What is significant about the nucleus in Eukaryotic cell structure?
Contains DNA and nucleolus; Site of DNA replication and Transcription
What is significant about the genetic information in Mitochondria?
Mitochondria contain circular mtDNA that is self-replicating
Cytoskeleton
Made up of microfilaments, microtubules, and intermediate filaments; Helps maintain structure of the cell and carry out basic functions
Plasma Membrane
Composed of phospholipid bilayer with lipid rafts and transmembrane proteins; regulates signaling and transport
Describe the phases of the Cell Cycle
Resting Phase: Cell carries out normal activities
Interphase: Preparation for division, DNA synthesized and G1/S and G2 checkpoints make sure that cell is ready for division
Mitosis: Cell Division
Describe the phases of Mitosis
Prophase: Nuclear membrane disappears, chromosomes condense, mitotic spindle forms
Metaphase: Chromosomes line up along metaphase plate
Anaphase: Chromosomes pulled apart
Telophase/Cytokinesis: Nuclear envelope and nucleolus reappear, cells divide
Describe the significantly different phases in Meiosis (as compared to mitosis)
Meiosis I: Two haploid daughter cells with duplicate sister chromatids
Prophase I: Homologous chromosomes pair up in synapsis, exchange genetic information in crossing over (meiosis + crossing over is a major source of genetic variability in sexual reproduction)
Bacteria
No membrane-bound organelles, no nucleus, circular genome
Describe the various bacteria shapes
Cocci = spheres
Bacilli = rods
spirilla = spirals
Obligate Aerobes
Require oxygen for metabolism
Obligate Anaerobes
Require oxygen-free environments for metabolism
Facultative Anaerobes
Can perform metabolism with or without oxygen
What do bacterial cell walls contain?
Peptidoglycan
Describe the difference between Gram-Positive and Gram-Negative bacteria
Gram-Pos: turn purple in gram staining; have thick peptidoglycan cell walls
Gram-Neg: Turn pink in Gram staining, have thin wall with outer lipopolysaccharide layer
Describe ribosomes in prokaryotes and eukaryotes
Prokaryotic Ribosomes (70S) are structurally different than eukaryotic ribosomes (80s)
Transformation
DNA from environment is absorbed
Transduction
Virus-mediated gene transfer
Conjugation
Like sexual reproduction for bacteria
Describe Viruses
Obligate intracellular parasites (need cell to multiply), protein capsid coat around genetic material
Lytic Cycle
Cellular machinery hijacked, host cell killed, explodes, releases viruses
Lysogenic Cycle
Virus incorporates itself into host genome and waits. Only in bacteriophages
What does the central dogma state?
Information flows from DNA to RNA to protein
What is a Codon?
Group of 3 RNA bases that code for amino acids; third position is “wobble”
What are the stop codons?
UAA, UAG, UGA (You are annoying, you are gross, you go away)
What is the start codon?
AUG (methionine)
What are the complementary base pairs?
A/T (U in RNA) & C/G
Describe the orientation of strands in DNA
Antiparallel
Describe the two different states DNA can be in as it is coiled around histones.
Euchromatin: Loose and transcriptionally active
Heterochromatin: Dense and transcriptionally inactive
What method describes DNA replication?
Semiconservative
Describe the actions of DNA polymerase (what direction does it read)
DNA polymerase reads 3’-5’ and synthesizes 5’-3’
Describe replication fluidity on leading and lagging strand
Replication is uninterrupted on leading strand; Interrupted on lagging strand - results in Okazaki fragments that are joined together using ligase
Describe the difference between the sense and anti-sense strands
In transcription, mRNA is synthesized from the antisense (template) strand; mRNA is therefore identical (except for U substituted for T) to the sense strand
Describe post transcriptional modifications
hnRNA is formed initially, undergoes 3’ poly-A tail addition (anti-degredation in cytoplasm), 5’ cap addition (transport and anti-degredation), and splicing (non-coding sequences (introns) removed and coding sequences (exons) ligated together) …. This all forms mRNA
Describe the general process of Translation
mRNA –> Protein; Occurs in ribosomes by tRNA (which is “charged” with amino acid residues”); tRNA builds proteins in ribosomes
Describe the difference between prokaryotic and eukaryotic ribosomes
Prokaryotic: 70s (30s + 50s)
Eukaryotic: 80s (40s + 60s)
Describe the steps of Translation (3); What are the binding sites for elongation?
Initiation, elongation, termination (binding sites for elongation are A, P, E)
Silent Mutations
Do not affect amino acids outcome (due to wobble)
Point mutations (missense mutations)
Conservative: Similar Amino Acids
Non-Conservative: Amino acids with different properties
Nonsense mutations
Premature stop codon
Insertions/Deletions
Frameshift mutations, change all downstream amino acids
Translocations
Larger-scale mutation: Swap of genetic material
Aneuploidy
Larger scale mutation: occurs due to nondisjunction during division
What is an Allele?
Specific variant of a given gene, such as round/wrinkled shape of peas
What is a test-cross?
Dominant-phenotype individual crossed with recessive individual to determine phenotype
Codominance
Two different alleles expressed at the same time (Example: Spotted Cow)
Incomplete Dominance
Blended phenotype in heterozygotes (red + white flower results in a pink flower)
What does the law of independent assortment state?
Inheritance of various genes not correlated with each other
Define Linkage
Exception to independent assortment; Genes physically close together on the same chromosome tend to have their alleles inherited together (Recombination frequency can be used to map location of genes on chromosomes)
Autosomal Inheritance vs. Sex-Linked Inheritance
Autosomal: Genes on non-sex chromosomes
Sex-linked: Genes on X chromosome
How do we characterize recessive inheritance versus dominant inheritance in a family tree?
Recessive inheritance skips a generation, while dominant inheritance usually does not
Describe how we determine if a gene is sex-linked by looking at a family tree
X-linked recessive traits affect more males than females because males only have one X chromosome; Therefore, inheritance of sex-linked traits is usually gender dependent
What are the 6 assumptions of the Hardy-Weinburg Equilibrium?
(1) Diploid sexual reproduction
(2) Random Mating
(3) Large population
(4) Random distribution of alleles by sex
(5) No mutations
(6) No migration
What is the equation for Hardy-Weinburg Equilibrium?
Define Fitness
Fitness is defined in terms of reproductive success
Define Speciation. What is it defined by?
Formation of a new species, defined by reproductive isolation (inability to produce fertile offspring with another species)
Stabilizing Selection
Extremes selected against, phenotype maintained within strict region
Directional Selection
One extreme selected against, phenotype moves to one end
Disruptive Selection
Middle selected against, population swings to favor both extremes
Describe the “molecular clock” method of dating divergence from last common ancestor.
Accumulation of random changes in genome over time is constant, therefore number of changes can help determine time
Define Gene Expression
Explains how cells with same DNA become different in development
Stem Cells
Stem cells are capable of differentiation, to varying extents
Totipotent Stem Cells
Can differentiate into any type of cell
Pluripotent Stem Cells
Can differentiate into any of the 3 germ layers
Multipotent Stem Cells
Have a more limited range of differentiation
What kind of cells have Operons?
Prokaryotic cells
Describe Positive vs. Negative Control in Operons
In negative control, a repressor prevents transcription
In positive control, an activator stimulates transcription
Describe the Lac Operon
Negative inducible; In absence of lactose, repressor blocks transcription. When lactose is present, allolactase disengages repressor, allowing transcription; Low Glucose levels upregulate transcription through CAP (positive control)
Describe the Trp Operon
Negative Repressible; Tryptophan is usually synthesized, but when already present, tryptophan causes repressor to bind to operator sequence and block transcription
Promoters (gene expression in Eukaryoties … Prokaryotes use operons)
Upstream DNA sequences that initiate transcription
Enhancers
DNA sequences that allow increased transcription
Transcription Factors
Proteins that regulate expression by binding to a specific DNA sequence
Heterochromatin
Dense, associated with transcriptional inactivity
Euchromatin
Loose, associated with transcriptional activity
Histone Acetylation
Increases transcription (loosens binding around histones)
DNA Methylation
Decreases transcription
siRNA and miRNA
Non-coding RNA that inhibits protein synthesis by blocking other RNA molecules
Cancer
Associated with mutations and altered gene expression patterns leading to uncontrolled proliferation of cells
Oncogenes
When oncogenes are turned on via mutations, they promote cell division and thus cancer
Tumor Suppressor Genes
Normally restrict cell division, when inactivated, cancer is more likely to develop
Restriction Enzymes
“Restriction Endonucleases”
Cut DNA at specific points, leading to blunt and sticky ends that can be recombined
How are plasmids and bacteriophage vectors related to Recombinant DNA?
Plasmid and bactoriophage vectors are used to transfer/amplify recombinant DNA
Electrophoresis
Laboratory technique that separates DNA & RNA molecules by size; Pulls molecules through agarose gel based on charge.
Hybridization (laboratory technique)
Refers to the ability of single strand DNA (or RNA) to jion with complementary base pair sequences; Used in southern, northern, and western blotting to detect specific DNA, RNA< and protein sequences, respectively
Polymerase Chain Reaction (PCR)
Laboratory technique used to make exponentially large numbers of copies of DNA in a short amount of time; Uses primers
Sanger Sequencing
Initial method for sequencing DNA; USes dideoxynucleotides to terminate DNA synthesis, then uses electrophoresis to analyze size of each fragment; This analysis can be used to piece strands of DNA together
Nervous System
The nervous system serves to take in and integrate information from the environment and allows the organism to respond appropriately
Central Nervous System
The central nervous system includes both the brain and the spinal cord. The various components of the brain are associated with key functions
Peripheral Nervous System
The peripheral nervous system is divided into the autonomic and somatic nervous systems.
Somatic Nervous System
The somatic nervous system controls voluntary responses via skeletal muscle
Autonomic Nervous System
The autonomic nervous system controls involuntary responses through the sympathetic (fight or flight) and the parasympathetic (rest and digest) systems
Neurons and Glial Cells
The functional unit of the nervous system is the neuron, and all neurons require supporting glial cells to function correctly
Glial Cells include oligodendrocytes, Schwann Cells, ependymal cells, satellite cells, astrocytes, and microglia
Types of Neurons
Neurons come in several types, including sensory cells that are bipolar and pseudounipolar, and motar and interneurons that are multipolar
Resting Potential
Neurons maintain a resting potential of -70mV by pumping sodium out and potassium into the cell. They maintain selective permeability that does not allow sodium ions or proteins bearing negatively charged resides to pass through the membrane
Neurons Transmit Information via Action Potentials. Describe this process.
- An action potential begins with a depolarization phase during which sodium rushes into the cell
- After peaking at +40 mV, the cell closes sodium channels and opens potassium channels. Potassium rushes out of the cell, repolarizing it
- The cell briefly hyper-polarizes with a potential below -70 mV. During this phase, it is much more difficult to stimulate a new action potential.
- The sodium-potassium pump re-establishes the resting state
What happens when the action potential reaches the end of the axon?
When the action potential reaches the end of the axon, the signal is transmitted to the post-synaptic membrane via a neurotransmitter
Calcium rushes in to the pre-synaptic axon terminal, which sends vesicles containing neurotransmitter into the synaptic cleft. The neurotransmitter binds to the post-synaptic membrane and serves as a catalyst for its effect
How are physics and physiology related (action potentials)
Neurons can be modeled both as concentration cells and as capacitors. The MCAT will want you to be familiar with these concepts from chemistry and physics and be able to apply them even if you are working through a biology passage.
Endocrine System
- Refers specifically to ductless glands that release signaling molecules (hormones) into the circulation
- Its role is communication among organ systems
- Endocrine signaling is slower than neural signaling
- Many endocrine functions are ultimately controlled by the nervous system (through intermediaries)
Structural Differences between peptide hormones, steroid hormones, and amino acid hormones, and how they contribute to the function of these hormone types
- Peptide hormones are made up from amino acid chains and are hydrophilic. Steorid hormones are derived from cholesteroal, have a four-ring structure, and are lipophilic
- Peptide hormones cannot diffuse through the plasma membranes of their target cells, so they interact with transmembrane receptors that activate second messenger signaling systems in the cytosol
- Steroid hormones can and do diffuse through the plasma membranes of their target cells, bind with receptors, and influence gene expression in their target cells
- Peptide hormones typically have quick-onset, short-acting effects. Steroid hormones typically have a delayed onset and long lasting effects
Steroid Hormones
Stoeroid hormones affect sex (estrogen, testosterone, progesterone), salt (aldosterone, a mineralocorticoid), and sugar (cortisal, a glucocorticoid).
Amino Acid Derived Hormones
Amino-acid derived hormones include T3/T4 and (nor)epinephrine. All other high-yield hormones are peptides
Negative Feedback
Common in the body; Downstream product inhibits upstream steps; Maintains homeostasis
Positive Feedback
Unusual in body; Downstream product upregulates upstream steps; pushes the body towards an extreme state; an example of this is oxytocin in labor/childbirth
Glucose (endocrine system)
Insulin decreases glucose, glucagon increases glucose
Serum Calcium Concentration (endocrine system)
PTH and calcitrol (active form of vitamin D) increase Ca2+, calcitonin decreases Ca2+
Fluids regulation (endocrine system)
Aldosterone and ADH increase fluid retention, ANP increases fluid excretion
Stress regulation (endocrine system)
Cortisol: increases glucose, long-term stress
Epinephrine: increases glucose and fight or flight response, short-term stress
Metabolic Rate regulations (endocrine system)
T3 and T4 increase basal metabolic rate
Reproduction and development regulations (endocrine system)
Estrogen and testosterone initiate and maintain secondary sex characteristics
Tropic Hormons
Play a role in multi-step signaling pathways
Path of a sperm through the male reporductive tract
seminiferous tubules –> epididymis –> vas deferens –> ejaculatory duct –> urethra –> penis
SEVEn UP (where “n” stands for nothing)
Path of Eggs through female reproductive tract
Ovaries –> Fallopian Tube, then:
If fertilization occurs –> Zygote/morula/blastocyst goes to uterus –> pregnancy –> childbirth through vaginal canal
In no fertilization occurs: Uterine lining shed during mensturation
Spermatogenesis
- Takes place in testes, which are maintained a few degress Celsius cooler than body temperature.
- Spermatogonial stem cells –> spermatogonia (2n) –> primary spermatocytes (2n) –> secondary spermatocytes (n) –> spermatids –> spermatozoa
Epididymis
Sperm mature and gain motility in epididymis
Spermatogenesis
A constant process from puberty throughout rest of lifespan
Oogenesis
Oogonia –> primary oocyte –> secondary oocyte + polar body –> ovum + polar body
Is oogenesis a constant process?
No, oogenesis is not a constant process. Primary oocytes are halted at prophase I at birth, meiosis I completed in the ovary to form secondary oocyte, which is then arrested at metaphase II. Meiosis II is completed at fertilization.
Fertilization
Takes place in fallopian tube; Acrosome reaction allows sperm cell to enter egg. Results in cortical reaction that prevents polyspermy.
Stages of Emrbyonic Development
- Morula (16-cell ball) –> Blastocyst (fluid-filled sac in the middle) –> gastrula (three germ cell layers present).
- Ectoderm –> Skin, nervous system, sweat glands, hair, nails
- Mesoderm –> connective tissue (including blood and bone), muscles, gonads
- Endoderm –> internal linings of GI tract, lungs, urinary bladder
Menstrual Cycle
Takes place every ~28 days in reproductive age women
Ovarian Cycle
Follicular phase (follicle develops), ovulation (egg is released), luteal phase (follicle –> corpus leuteum)
Uterine Cycle
Menstruation (uterine endometrium from previous cycle is shed), proliferative phase (endometrium develops again), secretory phase (endometrium is ready for implantation)
Hormones in Menstration Cycle
Estrogen gradually rises throughout follicular phase, triggering LH surge, which causes ovulation. Progesterone, secreted by corpus luteum, maintains uterine endometrium for implantation
If implantation happens, human chorionic gonadotropin (hCG) maintains corpus leuteum, thereby maintaining progesterone and maintaining pregnancy
Respiratory Anatomy
Nasal/oral cavity –> pharynx –> trachea –> bronchi –> bronchioles –> alveoli
Pleura surround lungs in the thoracic cavity. Surfactant covers alveoli to decrease surface tension and prevent them from collapsing.
Inspiration
Diaphragm contracts, expanding lungs; greater volume = lower pressure, air comes in from outside
Ciliated Cells and Mucus in respiratory tract
Ciliated cells and mucus in trachea and bronchi help trap particulate matter and push it up to be either expelled or swallowed
Basic point of respiration
Carbon dioxide produced as waste product of metabolism needs to be exhaled, and oxygen for aerobic respiration needs to be inhaled
Connection between CO2 and pH due to bicarbonate equilibrium
Blood Contents
Blood contains plasma (non-cellular component), platelets (thrombocytes), white blood cells (leukocytes) and red blood cells (erythrocytes)
Erythrocytes
Red blood cells; lack nuclei and membrane-bound organelles; rely on anaerobic metabolism, have biconcave shape, and are packed with hemoglobin (which carries oxygen and some carbon dioxide)
Basic Cardiovascular Anatomy
Venae Cave –> right atrium –> tricuspid valve –> right ventricle –> pulmonary semilunar valve –> pulmonary trunk and arteries –> capillaries (gas exchange) –> pulmonary veins –> left atrium –> bicuspid (mitral) valve –> left ventricle –> aortic semilunar valve –> aorta –> systemic circulation
Arteries vs. Veins
Arteries take blood away from the heart, while veins take blood back to the heart
Blood Vessels
Aorta > arteries > arterioles > capillaries > venules > veins > venae cavae
Pressure and Velocity in Circulatory System
Pressure decreases as blood moves through the circulatory system, and velocity decreases from arteries to capillary beds
Hemoglobin
A protein composed of four units, each with a heme group that contains an iron which binds oxygen
Hemoglobin-Oxygen Binding
Cooperative; Hemoglobin has T form, which is resistant to binding, and R form, which facilitates easier binding. The first bound oxygen stabilizes the R form.
Hemoglobin Dissociation Curve Shifts
Rightward shift of oxygen-hemoglobin dissociation curve means a lower affinity. Caused by increased CO2, increased H+, decreased pH (Bohr effect), increased 2,3-BPG, and increased temperature. Leftward shift means higher affinity. Caused by opposite of above conditions and in fetal hemoglobin.
Importance of Hemoglobin’s Biochemical properties
Biochemical properties of hemoglobin allow it to pick up oxygen in the lungs and deliver it to where it is needed in tissues undergoing active metabolism
Basic Path of Food through the digestive system
Oral Cavity –> Esophagus –> stomach –> small intestine (duodenum, jejunum, ileum) –> Large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon) –> Rectum
pH of Digestive System
Stomach has a very low pH due to gastric acid. pH becomes slightly alkaline in small intestine
Bile
Generate in liver, stored and concentrated in gallbladder, released to small intestine to emulsify fats
Pancreas
Secretes digestive enzymes and bicarbonate and releases them to small intestines
Small Intestine
Main site for digestion and absorption of nutrients; Villi multiply surface area of small intestinal lining; Microvilli on surface of cell increase surface area available for absorption
Large Intestine
Re-Absorption of H2O, large microbial comunity, absorption of microbe-generated substances (Vitamin K, short chain fatty acids)
Carbohydrates
Salivary amylase in mouth –> digestive enzymes (pancreatic amylase + disaccharidases) in small intestine –> Monosaccharides absorbed into small intestine cells –> Hepatic portal vein for liver processing –> bloodstream
Proteins
Pepsin in stomach –> Various peptidases in small intestines; isolated amino acids primarily absorbed in small intestine, as well as some dipeptides –> absorbed into small intestinal cells –> lacteals in villi –> drain into lymphatic system as chylomicrons –> bloodstream
Vitamins
Fat Soluble = A, D, E, K
Water Soluble = B and C
Function of Vitamins
Vitamins have a range of functions. Notably A helps in vision, D in calcium/phosphate regulation, K in clotting, C in collagen synthesis, and B vitamins are many important coenzymes/factors
Basic Urination Path
Glomerulus (blood vessels) –> capsular space of Bowman’s capsule –> proximal convoluted tubule –> Loop of Henle (descending limb and ascending limb), distal convoluted tubule –> collecting duct
Collecting duct –> minor calyx –> major calyx –> renal pelvis –> ureters –> urinary bladder –> urethra
Two Major Functions of the Nephron
(1) Filtering various substances in the blood
(2) Appropriately regulating fluid/salt content of urine
Loop of Henle
Loop of Henle has countercurrent multiplier mechanism to greatly reduce liquid volume in urine by first making urine concentrated (descending limp) then removing solutes (ascending limb)
Aldosterone
increased Na+ reabsorption = increased H2O reabsorption (especially in the presence of ADH) = increased plasma volume of blood = increased blood pressure
ADH
increased H2O retention = increased plasma volume of the blood = increased blood pressure
ANP
Decreased Na+ reabsorption = decreased H2O reabsorption = decreased plasma volume of blood = decreased blood pressure
Urinary System
Regulates blood pressure and blood volume, blood osmolarity and ion levels, pH, excretion of nitrogenous wastes and foreign substances
Antigen
Any substance that stimulates an immune response
Anitbody
Y-shaped molecule that recognizes antigens and allows an immune response to be mobilized. Has two heavy and two light chains linked by disulfide bonds
Anitgen-Antibody interactions
Lock lock in a key, antibodies are specific for specific antigens
Self/non-Self
Mediated by major histocompatibility complex (MHC) class I and II
MHC
Unique to every person
MHC Class I
Expressed in all nucleated cells, shows fragments of proteins from inside cell. Can be thought of as internal quality check. Abnormal in cases of viral infections or tumorigenesis. CD8+ T cells destroy.
MHC Class II
Expressed in some immune cells (macrophages, etc.), shows fragments of antigens from external invaders that have been engulfed; CD4+ helper T cells recruit response
Anatomical Barriers (innate immune system)
Skin, digestive enzymes, lysozymes in saliva/tears/breastmilk, mucociliary elevator in respiratory tract
White blood cells (innate immune system)
Neutrophils (phagocytose bacteria), NK cells, monocytes (differentiate into macrophages (“big eaters”) and dendritic cells), Eosinophils, and basophils
Complement (innate immune system)
Proteins involved in signaling cascade to tag pathogens, recruit phagocytes, and initiate inflammatory process
Cytokines (innate immune system)
Signaling proteins that coordinate immune response/inflammation. Interferons are cytokines that specialize in response to viruses
B cells (adaptive immune system)
Differentiate into plasma cells for antibody production. Produced in bone marrow and are activated in lymphatic organs or tissues. When activated, clonal expansion –> many copies
Short-lived plasma cells produce antibodies in response to current infection, memory cells remain present and react next time a threat appears
T-Cells (adaptive immune system)
Mature in thymus through positive/negative selection. Most are discarded.
CD4+ Helper T Cells (adaptive immune system)
Coordinate response to abnormal MHC class II (bacterial/fungal/other infection)
CD8+ Cytotoxic T Cells (adaptive immune system)
Kills cells with abnormal MHC class I (virus/tumor)
Other T Cells (adaptive immune system)
Suppressor T cells (also called regulatory T cells) moderate immune reaction when response has been sufficient.
Memory T cells “remember” previous antigens
Anatomy of Immune System
Bone marrow, lymphatic system, spleen, thymus, and other lymphatic tissues (appendix, tonsils, etc.)
Lymphatic System
Regulates fluid balance, is home for lymphocytes (B and T cells), drains fats from digestive system into bloodstream, returns substances from interstitial space to circulation
Connective Tissue
Includes bone, blood, adipose tissue as well as cartilage, ligaments, tendons (as well as a few other types)
Cartilage
Avascular, connective tissue
Ligaments
Tough tissue connecting bones to bones
Tendons
Tough tissue connecting muscles and bones
Bone Types
Long (ex. humerus, femur), flat (ex. skull), short (ex. wrist/ankle bones), sesamoid (ex. patella), irregular (ex. ethmoid)
Synovial Joints
Bones connected by lubricated synovial cavity (elbow)
Cartilaginous Joints
Bones connected by cartilage (vertebral discs)
Fibrous Joints
Bones connected by fibrous connective tissue (skull bones)
Joint Mobility Classifications
Diathrosis (freely movable), amphiarthrosis (slightly movable), synarthrosis (immovable)
Bone Matrix
Minerals (hydroxyapatite), collagen, water. Calcium/phosphate resevoir
Osteoblasts
Build up bone
Osteoclasts
Break down bone
PTH
increased Ca2+ from bone
Vitamin D
Increased Ca2+ from intestine
Calcitonin
Decreased Ca2+ in blood by inhibiting osteoclast activity
Bone Marrow
Hematopoiesis
Skeletal Muscle
Voluntary (somatic nervous system), striated, multinucleated. Red (slow-twitch) fibers contain abundant myoglobin, specialize in long-lasting actions requiring oxidative metabolism
White (fast-twitch) fibers contain less myoglobin and specialize in short bursts of action primarily using glycolysis
Smooth Muscle
Involuntary (autonomic nervous system), non-striated, uninucleate. Can undergo myogenic activity (contraction in absence of nervous stimulation)
Cardiac Muscle
Involuntary (autonomic nervous system), striated. Usually uninucleated. Sinoatrial node sets pace of contractions that can be modified by other signaling. Intercalated discs/gap junctions allow signals to spread
Muscle Contraction
Sliding actin/myosin filaments. ATP required to dissociate actin and myosin. ATP –> ADP to “cock” myosin head; Ca2+ binds to troponin which moves tropomyosin to allow actin and myosin to bind. Pi is released to generate power stroke
Sarcomere
I-band (thin filaments only), H-zone (thick filaments only), distances between M-lines (center of H-zone) and Z-lines (center of I-band) contract; A-band (entire area where thick filaments are present) stays the same during contraction
Layers of the Skin
From most superficial to deepest
Epidermins > dermis > hypodermis (although not technically part of the skin)
Epidermis
Contains layers of dead keratinocytes that provide physical protection, as well as melonocytes (pigment) and merkel cells (touch)
Dermis
Capillaries, lymph vessels, hair follicles, sweat glands, sensory cells
Skin heat regulation
Thermoregulation via sweating, vasoldilation/vasocontriction, piloerection
