Biology Flashcards
Nucleus
Contains all of the genetic material necessary for replication of the cell
Mitochondrion
Location of many metabolic processes (pyruvate dehydrogenase, CAC, ETC, oxidative phosphorylation, β-oxidation, some of gluconeogenesis, urea cycle) and ATP production
Lysosomes
Membrane-bound structures containing hydrolytic enzymes capable of breaking down many different substrates
Rough ER
Interconnected membranous structure with ribosomes studding the outside; site of synthesis for proteins destined for insertion into a membrane or secretion
Smooth ER
Interconnected membranous structure where lipid synthesis and detoxification occurs
Golgi apparatus
Membrane-bound sacs where posttranslational modification of proteins occurs
Peroxisomes
Organelle containing hydrogen peroxide; site of β-oxidation of very long chain fatty acids
Fluid mosaic model and membrane traffic
Phospholipid bilayer with cholesterol and embedded proteins
Exterior: hydrophilic phosphate head groups
Interior: hydrophobic fatty acids
Cell theory
All living things are composed of cells; the cell is the basic functional unit of life; cells arise only from preexisting cells
A fourth tenet has been added: cells carry genetic information in the form of DNA
Eukaryotes
Contain membrane-bound organelles such as a nucleus, while prokaryotes are simpler cells without a nucleus
Prokaryotes
All divide by binary fission; circular chromosome replicates and attaches to the cell wall; the plasma membrane and cell wall grow along the midline, forming daughter cells
Flagella
Eukaryotes: contain a basal body that serves as the engine for motion
Gram-positive
Have large quantities of peptidoglycan in the cell wall
Gram-negative
Have much smaller quantities of peptidoglycan with lipopolysaccharides
Shapes of bacteria
Cocci: spherical
Bacilli: rod-shaped
Spirilli: spiral-shaped
Cell division
G1: cell increases its organelles and cytoplasm
S: DNA replication
G2: same as G1
M: the cell divides in two
Mitosis: PMAT
Meiosis: PMAT X 2
Meiosis I
- Two pairs of sister chromatids form tetrads during prophase I
- Crossing over leads to genetic recombination in prophase I
- Homologous chromosomes separate during metaphase I
Meiosis II
- Essentially identical to mitosis, but no replication
- Meiosis occurs in spermatogenesis (sperm formation) and oogenesis (egg formation)
Four stages of early development
- Cleavage: mitotic divisions
- Implantation: embryo implants during blastula stage
- Gastrulation: ectoderm, endoderm, and mesoderm
- Neurulation: germ layers develop a nervous system
Ectoderm
“attract”oderm
- NS, epidermis, lens of eye, inner ear
Endoderm
“endernal” organs
- Lining of digestive tract, lungs, liver, and pancreas
Mesoderm
“means”oderm
- Muscles, skeleton, circulatory system, gonads, kidney
The liver’s role in homeostasis
- Gluconeogenesis
- Processing of nitrogenous wastes (urea)
- Detoxification of wastes/chemicals/drugs
- Storage of iron and vitamin A
- Synthesis of bile and blood proteins
- β-oxidation of fatty acids to ketones
- Interconversion of carbohydrates, fats, and AA
Layers of the skin
Stratum corneum, statum lucidum, stratum granulosum, stratum spinosum, stratum basalis
Osmoregulation
- Filtration at the glomerulus; filtrate (fluid and small solutes) passes through passive
- Secretion of acids, bases, and ions from interstitial fluid to filtrate; maintains pH, [K+] and [waste] passive and active
- Reabsorption: essential substances and water flow from filtrate to blood; enabled by osmolarity gradient and selective permeability of the walls passive and active
Aldosterone
Stimulates Na+ and water reabsorption
- Secreted from adrenal cortex in response to low blood pressure
- Regulated by the renin-angiotensin-aldosterone system
ADH (vasopressin)
Increases collecting duct’s permeability to water to increase water reabsorption
- Released from the posterior pituitary in response to high blood osmolarity
Four stages of the menstrual cycle
- Follicular: FSH causes growth of a follicle
- Ovulation: LH causes follicle to release egg
- Luteal: corpus luteum forms
- Menstruation: endometrial lining sheds
Mechanisms of hormone action
Peptides act via second messengers and steroids act via hormone/receptor binding to DNA; AA-derivative hormones may do either
Resting potential
- Na+/K+ ATPase creates gradient of high [Na+] outside the cell, and high [K+] inside
- Movement of ions down their concentration gradient through leak channels establishes resting potential
Action potential
- Stimulus acts on the neuron, depolarizing the membrane of the cell body
Impulse propagation
Depolarization (Na+ rushing into axon) followed by repolarization (K+ rushing out of axon) along the nerve axon
The synapse
- At the synaptic knob, voltage-gated Ca2+ channels open, sending Ca2+ into the cell
- Vesicles fuse with presynaptic membrane sending the neurotransmitter across the synaptic cleft
- Neurotransmitter binds to receptors on the postsynaptic membrane, triggering depolarization
Gates in action potential
I: Rest - all gates closed
II: Depolarization - Na+ gates open
III: Repolarization - Na+ gates inactive; K+ gates open
IV: Hyperpolarization - all gates closed
NS Flowchart
NS
Central: brain and spinal cord
Peripheral: sensory and motor - somatic and automatic - parasympathetic and sympathetic
Follicle-stimulating (FSH)
Source: anterior pituitary
Action: stimulates follicle maturation; spermatogenesis
Luteinizing (LH)
Source: anterior pituitary
Action: stimulates ovulation; testosterone synthesis
Adrenocorticotropic (ACTH)
Source: anterior pituitary
Action: stimulates adrenal cortex to make and secrete glucocorticoids
Thyroid-stimulating (TSH)
Source: anterior pituitary
Action: stimulates the thyroid to produce thyroid hormones
Prolactin
Source: anterior pituitary
Action: stimulates milk production and secretion
Endorphins
Source: anterior pituitary
Action: inhibits the perception of pain the brain
Growth hormone
Source: anterior pituitary
Action: stimulates bone and muscle growth/lipolysis
Oxytocin
Source: hypothalamus; stored in posterior pituitary
Action: stimulates uterine contractions during labor, milk secretion during lactation
Antidiuretic (ADH, vasopressin)
Source: hypothalamus; stored in posterior pituitary
Action: stimulates water reabsorption in kidneys
Thyroid hormones (T3, T4)
Source: thyroid
Action: stimulates metabolic activity
Calcitonin
Source: thyroid
Action: decreases (tones down) blood calcium level
Parathyroid hormone
Source: parathyroid
Action: increases blood calcium level
Glucocorticoids
Source: adrenal cortex
Action: increases blood glucose level and decreases protein synthesis; anti-inflammatory
Mineralocorticoids
Source: adrenal cortex
Action: increases sodium and water reabsorption in kidneys
Epinephrine, norepinephrine
Source: adrenal medulla
Action: increases blood glucose level and heart rate
Glucagon
Source: pancreas
Action: stimulates conversion of glucogen to glucose in the liver; increases blood glucose
Insulin
Source: pancreas
Action: lowers blood glucose; increases glycogen stores
Somatostatin
Source: pancreas
Action: suppresses secretion of glucagon and insulin
Testosterone
Source: testes
Action: maintains male secondary sex characteristics
Estrogen
Source: ovary/placenta
Action: maintains female secondary sex characteristics
Progesterone
Source: ovary/placenta
Action: promotes growth/maintenance of endometrium
Melatonin
Source: pineal
Action: regulates sleep-wake cycles
Atrial natriuretic peptide
Source: heart
Action: involved in osmoregulation and vasodilation
Thymosin
Source: thymus
Action: stimulates T-cell development
Sarcomere
- Contractile unit of the fibers in skeletal muscle
- Contains thin actin and thick myosin filaments
Initiation
Depolarization of a neuron leads to an action potential
Sarcomere shortening
- Sarcoplasmic reticulum releases Ca2+
- Ca2+ binds to troponin on the actin filament
- Tropomyosin shifts, exposing myosin-binding sites
- Myosin binds, ATPase activity allows myosin to pull thin filaments towards the center of the H zone, and then ATP causes dissociation
Relaxation
Ca2+ is pumped back into the sarcoplasmic reticulum
Bone formation and remodeling
- Osteoblast: builds bone
- Osteoclast: breaks down bone
- Reformation: inorganic ions are absorbed from the blood for use in bone
- Degradation (resorption): inorganic ions are released into the blood
Circulatory pathway through the heart
Super and inferior vena cava - right atrium - right ventricle - pulmonary arteries - lungs - pulmonary veins - left atrium - left ventricle - aorta - body
Three portal systems:
Blood travels through an extra capillary bed before returning to the heart
- Liver (hepatic), kidney, and brain (hypophyseal)
Fetal circulation
- Foramen ovale: connects right and left atria
- Ductus arteriosus: connects pulmonary artery to aorta; along with foramen ovale, shunts blood away from lungs
- Ductus venosus: connects umbilical vein to inferior vena cava, connecting umbilical circulation to central circulation
Plasma
Aqueous mixture of nutrients, wastes, hormones, blood proteins, gases, and salts
Erythrocytes (RBCs)
Carry oxygen
- Hemoglobin: four subunit carry O2 and CO2; iron controls binding and releasing
- Oxygen-hemoglobin dissociation: right shift of curve - increase temp, Bohr effect, decrease pH, increase pCO2, O2 release to tissues enhanced when H+ allosterically binds to Hb, increase pCO2 leads to increase [H+]
Leukocytes (WBCs)
Function in immunity
Platelets
Clotting
- Platelets release thromboplastin, which (along with cofactors Ca and vitamin K) converts inactive prothrombin to active thrombin
- Thrombin converts fibrinogen into fibrin, which surrounds blood cells to form the clot
Blood typing and Rh
- Blood cells with Rh factor are Rh+; these individuals produce no anti-Rh antibody.
- Rh- blood cells lack the antigen; these individuals produce an antibody if exposed
- If type A: antigen A, antibodies (anti-B)
Gas exchange
- Exchange occurs across the thin walls of alveoli
- Deoxygenated blood enters the pulmonary capillaries that surround the alveoli
- O2 from the inhaled air diffuses down its gradient into the capillaries, where it binds with hemoglobin and returns to the heart
- CO2 from the tissues diffuses from the capillaries to the alveoli, and is exhaled
Fetal respiration
- Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin
- Gas and nutrient exchanges occur across the placenta
Lipid digestion
- When chyme is present, the duodenum secretes the hormone cholecystokinin (CCK) into the blood
- CCK stimulates the secretion of pancreatic enzymes and bile and promotes satiety
- Bile is made in the liver and emulsifies fat in the small intestine; it’s not an enzyme
- Lipase is an enzyme made in the pancreas that hydrolyzes lipids in the small intestine
Salivary amylase (ptyalin)
Production site: salivary glands
Function site: mouth
Hydrolysis rxn: starch –> maltose
Pancreatic amylase
Production site: pancreas
Function site: sm intestine
Hydrolysis rxn: starch –> maltose
Maltase
Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: maltose –> 2 glucoses
Sucrase
Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: sucrose –> glucose, fructose
Lactase
Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: lactose –> glucose, galactose
Pepsin
Production site: gastric glands (chief cells)
Function site: stomach
Function: hydrolyzes specific peptide bonds
Trypsin
Production site: pancreas
Function site: sm intestine
Function: hydrolyzes specific peptide bonds; converts chymotrypsinogen to chymotrypsin
Chymotrypsin
Production site: pancreas
Function site: sm intestine
Function: hydrolyses specific peptide bonds
Carboxypeptidases A and B
Production site: pancreas
Function site: sm intestine
Function: hydrolyzes terminal peptide bond at C-terminus
Aminopeptidase
Production site: intestinal glands
Function site: sm intestine
Function: hydrolyzes terminal peptide bond at N-terminus
Dipeptidases
Production site: intestinal glands
Function site: sm intestine
Function: hydrolyzes part of AAs
Enteropeptidase
Production site: intestinal glands
Function site: sm intestine
Function: converts trypsinogen and procarboxypeptidases to active form
Memory cells
(B-lymphocyte)
- Remember antigen, speed up secondary response
Plasma cells
(B-lymphocyte)
- Make and release antibodies (IgG, IgA, IgM, IgD, and IgE) which induce antigen phagosytosis
Active immunity
Antibodies are produced during an immune response
Passive immunity
Antibodies produced by one organism are transferred to another organism
Cytotoxic T-cells
(T-lymphocytes)
- Destroy cells directly
Helper T-cells
(T-lymphocytes)
- Activate B- and T-cells and macrophages by secreting lymphokines
Suppressor T-cells
(T-lymphocytes)
- Regulate B- and T-cells to decrease anti-antigen activity
Memory cells
Also T-lymphocytes
Nonspecific immune response
Includes skin, passages lined with cilia, macrophages, inflammatory response, and interferons (proteins that help prevent the spread of a virus)
Lympathic system
- Lymph vessels meet at the thoracic duct in the upper chest and neck, draining into the left subclavian vein of the cardiovascular system
- Vessels carry lymph (excess interstitial fluid), and lacteals collect fats by absorbing chylomicrons in the sm. intestine
- Lymph nodes are swellings along the vessels with phagocytic cells (macrophages); they remove foreign particles from lymph
Law of segregation
Homologous alleles (chromosomes) separate so that each gamete has one copy of each gene
- If both parents are Rr, the alleles separate to give a genotypic ration of 1:2:1 and a phenotypic ration of 3:1
Law of independent assortment
Alleles of unlinked genes assort independently in meiosis
- For two traits: AaBb parents will produce AB, Ab, aB, and ab gametes
- The phenotypic ratio for this cross is 9:3:3:1
Genetic mapping
- Crossing over during meiosis I can unlink genes (prophase I)
- Genes are most likely unlinked when far apart
- One map unit is 1% recombinant frequency
Autosomal recessive
May skip generations
Autosomal dominant
Appears in every generation
X-linked (sex-linked)
No male-to-male transmission, and more males are affected
Hardy-Weinberg equilibrium
No mutations, large population, random mating, no migration, and equal reproductive success
p + q = 1; p^2 + 2pq + q^2 = 1
p: dominant allele
q: recessive allele
p^2: dominant homozygotes
2pq = heterozygotes
q^2: recessive homozygotes
Nucleic acids
Basic unit: nucleotide (sugar, nitrogenous base, phosphate)
- 2 types of bases: double-ringed purines (adenine, guanine) and single-ringed pyrimidines (cytosine, uracil, and thymine)
- A = T, C (triple)G
Structural genes
Have DNA that codes for protein
Operator gene
Repressor binding site
Promoter gene
RNA polymerase’s 1st binding site
Inducible systems
Need an inducer for transcription to occur
Repressible systems
Need a corepressor to inhibit transcription
Point mutation
One nucleotide is substituted by another; they are silent if the sequence of AA doesn’t change
Frameshift
Insertions or deletions shift reading frame; protein doesn’t form, or is nonfunctional
Viruses
Acellular structures of double- or single-stranded DNA or RNA in a protein coat
Lytic cycle
Virus kills the host cell
Lysogenic cycle
Virus enters the host genome
Plasmids
Extragenomic material; they can be integrated into the genome, but are then called episomes
Transformation
Occurs when a bacterium acquires a piece of genetic material from the environment and integrates that piece of genetic material into the host cell genome. This is a common method by which antibiotic resistance can be acquired
Conjugation
Bacterial form of mating (sexual reproduction)
- 2 cells forming a cytoplasmic bridge allowing for transfer of genetic material; transfer is from donor male (+) to recipient female (-)
- Bridge is made of sex pili; to form the pilus, bacteria must contain plasmids known as sex factors
Transduction
Occurs when a bacteriophage acquires genetic information from a host cell. Sometimes, when the new virions are assembled in a host cell is packaged along with the viral genetic material.
- Then, the bacteriophage infects another bacterium, resulting in transfer of bacterial genetic material
