MCAT Bio Flashcards
Describe the Cell Theory
The Cell Theory states that:
1) all living things are composed of cells
2) cells are the basic functional unit of life
3) cells arise only from pre-existing cells
4) cells carrry their genetic info in the form of DNA
Name the two distinct groups into which all celsl can be categorized
prokaryotes
eukaryotes
What is the key differentiating criterion between prokaryotic and eukaryotic cells
Eukaryotic celsl have membrane bound organelles; however, prokaryotic cells do not
T/F: Bacteria and viruses are examples of prokaryotic cells
False. Bacteria are prokaryotice cells but viruses are nonliving acellular structure
Describe bacterial DNA
Bacterial DNA consists of a single circular chromosome
What is a plasmid?
A smaller extrachromosomal ring of DNA sometimes found in bacteria.
It replicates independently of the bacterial chromosome
T/F: Bacteria contain ribosomes
True. BUT prokaryotic ribosomes are smaller than eukaryotic ribosomes
Name the components of a typical bacterial cell
cell wall, cell membrane, cytoplasm, flagella, DNA, ribosomes
Where does respiration occur in the bacterial cell?
the cell membrane is the site of respiration in bacteria
T/F: All multicellular organisms are composed of eukaryotic cells
True
Which type of eukaryotic cells have a cell wall?
Plant cells and fungal cells
What is cytosol?
The fluid component of cytoplasm
What are the primary components of the cytoskeleton?
the primary components of the cytoskeleton are:
1) microtubules
2) microfilaments
3) intermediate fibers
Define the fluid mosaic model
The fluid mosaic model states that a cell membrane consists of a phospholipid bilayer with proteins embedded throughout
Is the interior of the cell membrane hydrophilic or hydrophobic?
The interior of the cell membrane is hydrophobic
What is the function of a transport protein?
A transport protein helps move polar molecules and certain ions across the cell membrane
What is a membrane receptor?
A membrane receptor is a protein (or glycoprotein) that binds to molecules in the extracellular environment
Can small polar and non-polar molecules easily cross the cell membrane?
Yes, because of their size, small polar and non-polar molecules can easily traverse the cell membrane
How does a large charged molecule cross the cell membrane?
A large charged particle usually crosses the cell membrane with the help of a carrier protein
T/F: The nucleus is surrounded by a single-layered membrane
False. the nuclear membrane is double-layered.
How is material exchanged between the nucleus and the cytoplasm?
the nuclear membrane contains nuclear pores that selectively allow for the exchange of materials
What is a histone?
A histone is a structural protein complexed with eukaryotic DNA to form a chromosome
What is the function of the nucleolus?
The nucleolus synthesizes ribosomal RNA (rRNA)
What is the function of a ribosome?
The ribosome is the site of protein TRANSLATION (assembly) during protein synthesis
What is the general function of endoplasmic reticulum?
Endoplasmic reticulum is involved in the TRANSPORT of materials throughout the cell
What is the function of smooth endoplasmic reticulum (smooth ER)
Smooth ER is the site of :
1) lipid synthesis
2) poison detoxification
3) involed in protein transport within the cell
What is the function of rough endoplasmic reticulum (RER)?
RER serves as an attachment point for ribosomes, which functions in protein synthesis for membrane bound proteins and proteins to be excreted from the cell
T/F: Proteins synthesized by RER are secreted directly into the cytoplasm
False. they are secreted into the cisternae of the RER and then sent to smooth ER, where they are secreted into vesicles
What is the function of the Golgi apparatus?
The Golgi apparatus receives the vesicles from smooth ER, modifies them, repackages them into vesicles for distribution
What happens to a secretory vesicle after it is released from the Golgi apparatus?
A secretory vesicle from the Golgi fuses with the cell membrane and releases its contents via exocytosis
T/F: Vesicles and vacuoles are membrane-bound sacs involved in transport and storage of cellular materials
True
What is a lysosome?
A lysosome is a membrane-bound vesicle that contains hydrolytic enzymes involved in intracellular digestion
T/F: Lysosomes fuse with endocytotic vesicles and help digest their contents
True
How does the pH in the interior of a lysosome compare with the pH in the rest of the cell?
The interior of the lysosome is acidic and therefore has a lower pH than the rest of the cell
What would happen if a lysosome released its contents into the cytoplasm?
The hydrolytic enzymes of the lysosome would digest the organelles and kill the cell. This process is known as AUTOLYSIS
What is the function of peroxisomes?
Peroxisomes make hydrogen peroxide and digest fats into smaller molecules
What is the function of mitochondria?
Mitochondria are the sites of aerobic respiration and supply most of the cell’s energy
T/F: Mitochondria have their own circular DNA
True
Do mitochondria replicate in a manner similar to a cell’s other organelles?
No, they replicate via binary fission
T/F: Mitochondria and chloroplasts are similar structures and both are considered to be semi-autonomous
True
What is the function of a cell wall?
A cell wall protects the cell from external stimuli and desiccation.
What is the function of centrioles
Centrioles are involved in spindle formation during cell replication. They are found only in animal cells
What is a centrosome?
The centrosome is the region of a cell that contains the centrioles
What is the function of the cytoskeleton?
The cytoskeleton:
1) gives mechanical support
2) maintains the cell’s shape
3) and functions in motility
What is the function of microtubules?
Microtubles:
1) maintain cell shape
2) form the spindle apparatus and
3) provide tracks along which organelles can move
T/F: Cilia and flagella are specialized arrangements of microfilaments and function in cell motility
False, while cilia and flagella do function in cell motility, they are composed of microtubules.
T/F: Microfilaments are solid rods of actin and are involved in cell movement and cell wall support
True.
T/F: Simple diffusion is a passive process that requires energy.
False, simple diffusion is a passive process and therefore DOES NOT require energy
Define osmosis
Osmosis is the simple diffusion of water from a region of lower solute concentration to a region of higher solute concentration
What would happen to a cell if it were put in a hypertonic solution?
A hypertonic solution would cause water to flow out of a cell and cause the cell to shrink.
T/F: A hypotonic solution will cause water to flow into a caell, causing it to swell
True
Define isotonic
A medium and a cell are isotonic when the solute concentrations of the medium and the cell are equal
Define facilitated diffusion
Facilitated diffusion is the net movement of dissolved particles down their concentration gradient with the help of carrier molecules
T/F: Facilitated diffusion requires energy
False, all forms of diffusion, including facilitated diffusion are passive processes
Define active transport
Active transport is the net movement of dissolved particles against their concentration gradient with the help of carrier molecules. This process requires ATP
T/F: Active transport requires energy
True
What is endocytosis?
Endocytosis is a process in which the cell membrane invaginates, forming an intracellular vesicle containing extracellular medium
What is exocytosis?
Exocytosis is a process in which a vesicle within the cell fuses with the cell membrane and releases its contents to the extracellular medium
What is the difference between pinocytosis and phagocytosis?
Pinocytosis is the endocytosis of liquids and small particles, whereas phagocytosis is the ednocytosis of large particles.
What are the four basic types of tissue found in the body?
The four basic types of tissue found in the body are:
1) epithelial
2) connective
3) nervous
4) muscle
What are the components of a virus?
A protein coat and nucleic acid
What kinds of nucleic acid are found in viruses?
Single or double stranded DNA or RNA
T/F: Viruses are obligate intracellular parasites
True
What is a bacteriophage?
A bacteriophage is a virus that infencts bacteria only
What is the genetic material of a virus?
The genetic material of a virus can be DNA or RNA
How do enzymes speed up a reaction?
Enzymes are proteins catalysts that accelerate a reaction by reducing the amount of activation energy required
T/F: Enzymes get used up during the course of a reaction
False, enzymes are catalysts and therefore don’t get used up during the course of a reaction
T/F: Enzymes are very selective in teh reactions they catalyze
True
What is a substrate?
A substrate is a molecule upon which an enzyme acts
What is an active site?
An active site is the area of an enzyme to which a substrate binds
What is the lock and key theory?
The lock and key theory states that an enzyme and its corresponding active site are exactly complementary
T/F: The induced fit hypothesis holds that an enzyme causes a conformational change in its corresponding active site to facilitate substrate binding.
True
What is a cofactor?
A cofactor is a nonprotein molecule that is incorporated in an enzyme and is required for proper functioning
What is the difference between an apoenzyme and a holoenzyme?
An apoenzyme is an enzyme without its corresponding cofactor. A holoenzyme contains its cofactor.
What is a coenzyme?
A coenzyme is an organic cofactor for an enzymatic reaction (e.g. vitamin)
What is a prosthetic group?
A tightly bound cofactor is also known as a prosthetic group
T/F: Most coenzymes are synthesized by the body
False, most coenzymes are obtained from outside sources
What happens to the free energy (delta G) of a reaction if it is catalyzed by an enzyme?
The free energy of an enzyme-catalyzed reaction is the same as the reaction without the enzyme
What happens as the concentration of substrate is increased in an enzyme-catalyzed reaction?
The reaction rate increases until most of the active sites are filled and then the reaction rate reaches a plateau
T/F: A very high concentrations of substrate, reaction rate approximates Vmax
True
T/F: All enzymes in the body are proteins
False, ribozymes are RNA enzymes
What is the optimal pH for the enzymes of glycolysis
7
What is the optimal temperature for most enzymes in the body?
37 degrees Celsius
T/F: All enzymes in the body operate most efficiently at a pH of around 7.2
False, enzymes in the digestive tract work best at acidic and basic pH’s
What is an allosteric enzyme?
An allosteric enzyme is an enzyme with two or more active sites. An allosteric enzyme oscillates between an active and inactive configuration
What happens to an enzyme in the presence of an allosteric inhibitor?
An allosteric inhibitor prevents an enzyme from binding to its substrate by stabilizing the inactive configuration
What are the three categories of enzymatic regulatory inhibition?
1) Feedback
2) Reversible
3) Irreversible inhibition
How does feedback inhibition regulate an enzymatic process?
Feedback inhibition uses an end product as an allosteric inhibitor to the enzyme catalyzing the reaction
What are the two types of reversible inhibitors?
The two types of reversible inhibitors are competitive and non-competitive inhibitors
T/F: A non-competitive inhibitor can be overcome by increasing the concentration of substrate
False, a non-competitive inhibitor doesn’t bind at the active site and therefore doesn’t compete with the substrate
T/F: A competitive inhibitor binds at the active site and therefore can be overcome by increasing the concentration of substrate
True, a competitive inhibitor competes with the substrate for active sites
How can a non-competitive inhibitor’s effect be reversed?
Through the addition of a compound having a greater affinity for the inhibitor than the inhibitor has for the enzyme
T/F: Irreversible inhibition involves permanent damage to the active site
True
What is a zymogen?
A zymogen is an inactive form of an enzyme
How is a zymogen activated? Give some examples of zymogens
A zymogen is activated when a part of it is cleaved off. A few examples are digestive enzymes such as pepsinogen and chymotrypsinogen. (Note the “ogen” suffix”
What is an anabolic process?
An anabolic process is a reaction that builds complex molecules and requires energy
What is a catabolic process?
A catabolic process is a reaction that breaks down complex molecules and releases energy
What is an autotroph?
An autotroph is an organism that can harness sunlight to create energy via photosynthesis (e.g. plants)
What is a heterotroph?
A heterotroph is an organism that breaks down organic nutrients for energy
What are the energy carrier molecules for a cell’s metabolic processes?
ATP, NAD+, NADP+, and FAD
How do ATP, NAD+, NADP+, and FAD store energy?
ATP stores energy in its high-energy phosphate bonds. NAD+, NADP+ and FAD store energy in high-potential electrons
Does oxidation result in the loss or gain of electrons?
Oxidation refers to the loss of electrons. think: OIL RIG
What happens to the number of electrons when a reactant gets reduced?
Reduction results in the gain of electrons
T/F: An oxidizing agent gets oxidized during a reaction
False, an oxidizing agents gets reduced and thereby causes another molecule to be oxidized
What is the net reaction for glycolysis?
Glucose + 2ADP + 2Pi + 2 NAD+ —–> 2Pyruvate + 2ATP + 2NADH + 2H+ +2H2O
GAP N PANN HH
T/F: Glycolysis results in substrate level phosphorylation of ADP
True
Is glycolysis an aerobic or anaerobic process?
Glycolysis is an anaerobic process
What are the possible products of fermentation?
The products of fermentation are either ethanol or lactic acid
When does a cell rely on fermentation for its energy needs?
A cell utilizes fermentation in an anaerobic (oxygen deficient) environment
What is the net gain in ATP from cellular respiration?
Eukaryotes = 36 ATP; Prokaryotes = 38 ATP
T/F: Cellular respiration requires aerobic conditions
True
What are the three stages of cellular respiration?
The 3 stages of cellular respiration are:
1) pyruvate decarboxylation
2) the citric acid (Krebs) cycle
3) electron transport chain
T/F: During pyruvate decarboxylation, a molecule of CO2 is lost, leaving acetyl CoA
True
One molecule of glucose requires how many turns of the citric acid cycle?
The citric acid cycle (TCA) completes 2 cycles (turns) per molecule of glucose
How many ATP, NADH, and FADH2 are created in one turn of the citric acid cycle?
Each turn of the citric acid cycle results in 1 GTP, 3 NADH, and 1 FADH2
What is a cytochrome?
A cytochrome is a molecular electron carrier involved in oxidative phosphorylation
When and where does oxidative phosphorylation occur?
Oxidative phosphorylation occurs at the inner mitochondrial membrane during the electron transport stage of cellular respiration
Does the electron transport chain require oxygen?
Yes, the final acceptor of the electrons is O2 (oxygen) which then forms water
T/F: the electron transport chain generates a proton gradient across the inner mitochondrial membrane.
True
Where does glycolysis occur?
Glycolysis occurs in the cytoplasm
Where does the citric acid cycle occur?
The citric acid cycle occurs in the inner mitochondrial matrix
T/F: If glucose is unavailable, the body can use carbohydrates, fats, and proteins to create energy
True. Gluconeugenesis
What are the four stages of the cell cycle?
The 4 stages of the cell cycle are:
1) G1
2) S
3) G2
4) M
When do a cell’s chromosomes replicate?
The chromosomes replicate during the S (synthesis) stage of interphase
What is the order of the four stages of mitosis?
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
What is a chromatid?
A chromatid is one half of a replicated chromosome. Sister chromatids are attached by the centromere.
In which mitotic phase does spindle formation occur?
Spindle formation occurs during prophase
In which mitotic phase are the chromosomes lined up in the equatorial plane?
The chromosomes line up during metaphase
In which mitotic phase do the chromosomes separate?
The chromosomes separate during anaphase
In which mitotic phase does cytokinesis occur?
Cytokinesis occurs during telophase
How many chromosomes are in a human diploid cell?
human diploid cell = 46 chromosomes
How many chromosomes are in a human haploid cell?
human haploid cells= 23 chromosomes
What is a gametocyte?
A gametocyte is a haploid cell that undergoes meiosis
T/F: Homologous chromosomes code for different traits.
False, homologous chromosomes code for the same traits
In what phase of meiosis would one find a tetrad?
Tetrads exist in Prophase I
T/F: Synapsis and crossing over result in genetic recombination
True
name the different structures of the male reproductive tract
SEVEN UP: Seminiferous tubules (testes) epididymis vas deferens ejaculatory duct (nothing) urethra penis
What is the sequence of development for a mature sperm cell?
Primary spermatocyte
secondary spermatocyte
spermatid
spermatozoa
What is an acrosome?
An acrosome is the enzyme-containing cap-like structure on the head of a sperm
T/F: At birth, a female child’s ova are arrested at prophase 1 and are called primary oocytes
True
Starting with the ovary, name the different structures of the female reproductive tract
Ovary oviduct (fallopian tube) uterus cervix vagina
What are the corona radiata and zona pellucida?
The corona radiata is the outer layer of cells that surrounds the ovum. The zona pellucida is in the inner layer of cells that surrounds the ovum
What is a polar body?
A polar body is a small cell taht results from unequal distribution of cytoplasm during meiosis
T/F: Dizygotic (fraternal) twins are identical
False, monozygotic twins are identical
Order the following embryonic stages: blastula, neurula, morula, gastrula, zygote
Zygote Morula Blastula Gastrula Neurula
What is differentiation?
Differentiation is the specialization of cells that occurs during development
What are the 3 primary germ layers?
Ectoderm, endoderm, and mesoderm
What is induction?
Induction is the influence of a group of cells upon the differentiation of another group of cells
Match the following structures with the stage of development in which they first appear:
- Inner cell mass
- Archenteron
- Notochord
- Trophoblast
- Blastopore
- Neural fold
a. Blastula
b. Gastrula
c. Neurula
1a (Inner cell mass/Blastula 2b Archenteron/Gastrula 3c Notochord/Neurula 4a Trophoblast/Blastula 5b Blastopore/ Gastrula 6c Neural fold/Neurula
What structures arise from ectoderm?
Ectoderm:
integument
lens of the eye,
nervous sytem
What structures arise from endoderm?
Endoderm: epithelial linings of digestive and respiratory tracts parts of liver pancreas thyroid bladder
What structures arise from mesoderm?
Mesoderm: musculoskeletal system circulatory system connective tissue excretory system gonads
T/F: the placenta and umbilical cord are responsible for fetal respiration, nutrition, and waste removal.
True
T/F: Adult hemoglobin has a higher affinity for oxygen than fetal hemoglobin
False, fetal hemoglobin has a higher affinity for oxygen
What is the function of the ductus venosus”
The ductus venosus shunts blood away from teh fetal liver
What is the function of the foramen ovale?
The foramen ovale diverts blood away from the pulmonary arteries and into the left atrium
What is the function of the ductus arteriosus?
ductus arteriosus shunts blood directly from the pulmonary artery into the aorta.
In what trimester does the fetal heart begin to beat?
The heart begins to beat in the first trimester
In what trimester do the skeleton and organs form?
The skeleton and organs are formed during the first trimester
T/F: The allantois and yolk sac form the basis of the umbilical cord
True
From what structure does the placenta originate?
The placenta originates from the chorion
What are the functions of the skeleton?
The functions of the skeleton are:
1) physical support
2) protection of delicate organs (e.g. brain)
3) source of blood cells (i.e. bone marrow)
What are the two major components of the skeleton?
The major components of the skeleton are:
cartilage
bone
Which type of cells secrete cartilaginous tissue?
Chondrocytes secrete cartilaginous tissue
What are the two types of bone?
The two types of bone are:
compact bone
spongy bone
What is periosteum?
The periosteum is the fibrous sheath of a bone
What is the function of an osteoclast?
Osteoclasts are involved in bone reabsorption
What is the function of an osteoblast?
Osteoblasts are involved in bone formation
Name the components of the osteon (Haversian system)
- Lamellae
- Osteon
- Canaliculi
- Lacuna
- Haversian canal
T/F: Endochondral ossification is the replacement of cartilage with bone.
True
What is intramembranous ossification?
Intramembranous ossification is the transformation of mesenchymal tissue into bone
What is the function of a ligament?
Ligaments connect bone to bone and strengthen joints
What is synovial fluid?
Synovial fluid is a lubricant found in movable joints
What are the 3 distinct types of muscle in mammals?
The three types of muscle are:
1) skeletal
2) cardiac
3) smooth
What is the sarcoplasmic reticulum?
The sarcoplasmic reticulum is a modified endoplasmic reticulum that stores calcium ions (in a muscle cell).
T/F:Within a sarcomere, thick filaments are made of actin and thin filaments are made of myosin
False, thin filaments are made of actin and thick filaments are made of myosin
During contraction, what happens to the width of the A-band?
The A band is always of constant width
During contraction, what happens to the H zone and the I band
The H zone and the I band contract and decrease in length
T/F: The release of Ca 2+ by the sarcoplasmic reticulum initiates muscle contraction
True
T/F: The sarcoplasmic reticulum must uptake Ca 2+ for relaxation to occur
True
T/F: A muscle fiber exhibits an “all-or-nothing” response
True
Which component of the nervous system innervates smooth muscle?
Smooth muscle is innervated by the autonomic nervous system
Which types of muscles are striated?
Cardiac and skeletal muscle are striated
Which types of muscle display myogenic activity?
Cardiac and smooth muscle display myogenic activity
What is the role of calcium in the initiation of sarcomere contraction?
Calcium binds with troponin, which causes a conformational shift in tropomyosin, expressing the myosin binding site.
Which compound is needed to release myosin from its binding site on actin?
ATP is needed to release myosin from its binding site on actin
Name the structures of the human alimentary canal
Oral cavity pharynx esophagus stomach small intestine large intestine
What enzyme does saliva contain and what does it digest?
Salivary amylase, which digests starch (carbohydrates)
T/F: Chief cells secrete HCl into the stomach
False, chief cells secrete PEPSINOGEN into the stomach.
Parietal cells secrete HCl into the stomach
What is peristalsis?
Peristalsis is defined as the wave-like smooth muscle contractions that propel food through the digestive tract
What do parietal cells secrete into the stomach?
Parietal cells secret HCl into the stomach
What two sphincters separate the stomach from the rest of the alimentary canal?
The cardiac sphincter and the pyloric sphincter
What are the three segments of the small intestine?
The small intestine is divided into the:
1) duodenum
2) jejunum
3) ileum
Which segment(s) of the small intestine is/are primarily responsible for digestion?
Duodenum is primarily responsible for digestion
Which segment(s) of the small intestine is/are primarily responsible for absorption?
The jejunum and ileum are primarily responsible for absorption
Why is pancreatic juice basic (high pH)?
Pancreatic juice contains bicarbonate ion, which serves to neutralize the acidic chyme from the stomach. This is necessary because pancreatic enzymes work best at a slightly basic pH.
T/F: Bile is manufactured in the liver, stored in the gall bladder, and facilitates lipid digestion
True
What are the 3 components of the large intestine?
The large intestine is divided into the:
1) cecum
2) colon
3) rectum
What is the primary function of the large intestine?
The large intestine function primarily to absorb water and salts
Where do protein digestion and lipid digestion begin?
Protein digestion begins in the stomach and lipid digestion begins in the small intestine
Which component of the nervous system inhibits digestion? Which component promotes digestion?
The sympathetic nervous system inhibits digestion. The parasympathetic nervous system stimulates digestion.
Match the following enzymes with their site of function and the nutrient they digest:
- Chymotrypsin
- Pepsin
- Lipase
- Sucrase
- Trypsin
- Carboxypeptidase
- Maltase
- Salivary amylase
a. Mouth
b. Stomach
c. small intestine
d. large intestine
e. Starch
f. Protein
g. Lipid
- c,f
- b,f
- c,g
- c,e
- c,f
- c,f
- c,e
- a,e
remember:
small intestine = chymotrypsin, lipase, sucrase, trypsin, carboxypeptidase, and maltase.
and chymotrypsin, pepsin, trypsin, carboxypeptidase work on PROTEINS
CORRECTLY sequence the following structures of the respiratory tract:
alveoli, trachea, larynx, nares, pharynx, bronchi, bronchioles
Nares Pharynx Larynx trachea bronchi bronchioles alveoli
What is the function of surfactant?
Surfactant reduces surface tension on alveoli and facilitates gas exchange
T/F: The diaphragm contracts during exhalation
False, the diaphragm relaxes during exhalation and contracts during inhalation
Which part of the brain controls breathing?
the medulla oblongata controls breathing
Define vital capacity
Vital capacity is the maximum amount of air that can be inhaled
Define tidal volume
Tidal volume is the normal amount of air inhaled
Define residual volume
Residual volume is air that always remains in the lungs
T/F: Total lung capacity = tidal volume + residual volume
FALSE, total lung capacity = vital capacity + residual volume
What happens to respiratory rate when high concentrations of CO2 and/or H+ are in the blood
Respiratory rate increases
T/F: Blood entering the pulmonary capillaries has a higher partial pressure of O2 than the air in the alveoli
False, O2 partial pressure is lower in the pulmonary capillary blood than in the alveolar air
How does the partial pressure of CO2 in a capillary compare with the partial pressure of CO2 in alveolar air?
The partial pressure of CO2 in the capillaries is higher than in the alveolar air
T/F: All arteries carry oxygenated blood and all veins carry deoxygenated blood
False, pulmonary arteries and umbilical arteries carry deoxygenated blood, while pulmonary veins and umbilical veins carry oxygenated blood
T/F: The right side of the heart pumps blood into pulmonary circulation and the left side pumps blood into systemic circulation
True
Starting with the right atrium, trace the path of blood flow throughout the body.
RIGHT ATRIUM RIGHT VENTRICLE pulmonary arteries pulmonary capillaries pumlonary veins
LEFT ATRIUM LEFT VENTRICLE AORTA arteries arterioles capillaries venules veins vena cava
Which valve separates the right atrium and right ventricle?
The tricuspid valve separates the right atrium from the right ventricle.
((always TRI before you BI))
Which valve separates the left atrium and left ventricle?
the bicuspid valve (or mitral valve) separates the left atrium from the left ventricle
T/F: Systole is when the heart relaxes and diastole is when the ventricles contract
False, the ventricles contract during systole and the heart relaxes during diastole
What is the electrical pathway in the heart?
Electrical conduction pathway:
sinoatrial node –> atrioventricular node –> bundle of His –> Purkinje fibers
Which nerve of the parasympathetic nervous system decreases heart rate?
The vagus nerve
Which component of the nervous system increases heart rate?
Sympathetic nervous system stimulation causes an increase in heart rate
What is the plasma?
Plasma is the liquid component of blood
What are the cellular components of blood?
The cellular components of blood are:
1) erythrocytes (red blood cells)
2) leukocytes (white blood cells)
3) platelets
T/F: The three types of leukocytes are granular leukocytes, lymphocytes, and monoctyes
True
Which type of leukocyte plays a key role in inflammation and allergic reactions?
Granular leukocytes (basophils, eosinophils and neutrophils) are active in inflammation and allergic reactions
Which type of leukocyte plays a key role in immune response?
Lymphocytes are key players in immune response
What is the function of a monocyte?
A monocyte phagocytizes foreign matter
What are the four blood types?
A, B, AB, and O
Which blood type is considered to be a universal donor? Which type is a universal recipient?
O = universal donor
AB= universal recipient
What is the Rh factor? How can the Rh factor complicate pregnancy?
The Rh factor is an antigen on the surface of RBCs. Following the birth of an Rh+ child, an Rh- mother develops antibodies to the Rh factor. These antibodies can attack the blood cells of any future Rh+ fetuses carried by the mother.
According to the Bohr effect, would high levels of H+ and HCO3- increase or decrease hemoglobin’s affinity for O2?
High levels of H+ and HCO3 would decrease hemoglobin’s affinity for O2
T/F: Platelets play a key role in the immune response
False, platelets are keys players in clot formation
Which proteins are essential for proper clotting?
Thrombin and fibrin are essential for clot formation
T/F: B lymphocytes are involved in humoral immunity
True
What is the function of immunoglobins (antibodies)?
Antibodies attract other cells that can phagocytize an antigen or cause the antigens to clump together
What role do T Lymphocytes play in an immune response?
T Lymphocytes are involved in cell-mediated immunity. They are responsible for the body’s defense against viral and fungal infections
T/F: Skin, ciliated mucosa, macrophages, and inflammatory responses are all examples of nonspecific defense mechanisms
True
What happens to interstitial fluid that doesn’t diffuse into a capillary?
Excess interstitial fluid is picked up by the lymphatic system and returned to the circulatory system
What is a lymph node and what is its function?
A lymph node is swelling along a lymphatic vessel that contains phagocytic cells. Their role is to filter the lymph and remove/destroy foreign particles
Define homeostasis
The maintenance of a stable internal environment
What are the primary homeostatic organs in mammals?
The primary homeostatic organs are the:
1) kidneys
2) liver
3) large intestine
4) skin
What are the three regions of a kidney?
The 3 regions of the kidney are the:
1) pelvis
2) medulla
3) cortex
T/F: A nephron is situated such that the loop of Henle runs through the medulla
True
What is the primary purpose of the kidney?
The primary purpose of the kidneys is to regulate salt and water concentration in the blood
Where are amino acids, glucose, and vitamins reabsorbed in the nephron?
Amino acids, glucose and vitamins are reabsorbed into the proximal convoluted tubule
Where in the loop of Henle does water passively diffuse out?
Water passively diffuses out of the descending limb
T/F: Water passively diffuses into the ascending limb
False, the ascending limb is impermeable to water.
T/F: Aldosterone stimulates the reabsorption of Na+ and H2O from the distal tubule and collecting duct
True
Would high levels of aldosterone result in concentrated or dilute urine?
High levels of aldosterone result in CONCENTRATED URINE
How would low levels of aldosterone affect blood pressure?
Low levels of aldosterone lead to reduced blood plasma volume and therefore REDUCED blood pressure
Would high levels of ADH (vasopressin) result in concentrated or dilute urine?
High levels of ADH result in CONCENTRATED URINE
Where and how does ADH affect the nephron?
ADH makes the distal convoluted tubule and collecting duct MORE permeable to H2O
T/F: Urine leaves the kidney via the ureter and leaves the bladder via the urethra
True
Is urine hypertonic or hypotonic to blood?
Urine is hypertonic to blood
What are some functions of the liver?
Liver functions include:
1) regulation of blood glucose
2) detoxification of toxins
3) beta-oxidation of fatty acids
4) destruction of old red blood cells
T/F: The large intestine funcitons as an excretory organ by getting rid of excess salts
True
In which layer of the skin are sweat glands, sense organs, and blood vessels located?
they are all located in the dermis
T/F: Constriction of blood vessels in the skin leads to decreased body temperature
False, constriction of blood vessels in the skin leads to increased body temperature
What is the difference between an endocrine gland and an exocrine gland?
Endocrine glands secrete their hormones directly into the blood stream.
Exocrine glands secrete substances that are transported by ducts.
What is the difference between a tropic hormone and a direct hormone?
Tropic hormones stimulate other endocrine glands, while direct hormones act directly on the target organ
The anterior pituitary is regulated in part by what other endocrine gland?
The hypothalamus regulates the anterior pituitary
Name all of the hormones secreted by the anterior pituitary
FSH: follicle-stimulating hormone LH: luteinizing hormone ACTH: adrenocorticotropic hormone TSH: thyroid stimulating hormone Prolactin Endorphins GH: growth hormone
T/F: Growth hormone promotes bone and muscle growth
True
What is the function of prolactin?
Prolactin stimulates the production of breast milk
What is the target gland of ACTH?
ACTH acts on the adrenal cortex
What is the function of TSH?
TSH causes the thyroid to uptake iodine and produce thyroid hormone
T/F: LH and FSH are secreted only in females.
False, LH and FSH are produced and secreted in males as well as females
Name the hormones synthesized by the posterior pituitary
None! The posterior pituitary stores hormones (oxytocin and ADH) that are synthesized in the hypothalamus
What 2 hormones are released by the posterior pituitary and what are their functions?
Oxytocin increases the strength of contractions during childbirth. Antidiuretic hormone (ADH, vasopressin) promotes the absorption of water in the nephron
T/F: the hypothalamus regulates both the anterior and the posterior pituitary through hormone secretion and neurosecretory cells
True
Name the hormones secreted by the thyroid gland
The thyroid gland secretes thyroxine (T4) and triiodothryonine (T3) (collectively known as thyroid hormones) as well as calcitonin
How do thyroid hormones affect metabolism?
Thyroid hormones increase metabolism
How does calcitonin affect the level of Ca2+ in blood plasma?
Calcitonin decreases blood plasma Ca2+
What hormone does the parathyroid gland produce and what is its function?
The parathyroid secretes parathyroid hormone , which serves to increase blood plasma Ca2+
Name the 3 types of hormones secreted by the adrenal cortex
the 3 types of hormones are:
1) glucocorticoids
2) mineralocorticoids
3) cortical sex hormones
What is the function of cortisol?
Cortisol is a glucocorticoid that increases the blood’s glucose level
What important mineralocorticoid is released by the adrenal cortex?
Aldosterone is an important mineralocorticoid released by the adrenal cortex
Which endocrine gland secretes epinephrine and norepinephrine?
The adrenal medulla secretes epinephrine and norepinephrine
T/F: Epinephrine and norepinephrine return the body to its resting state and increase nutrient absorption
False, they slow down digestion and increase the basal metabolic rate
What are some of the effects of epinephrine?
Epinephrine effects include:
1) Increased heart rate
2) increased blood glucose level
3) Increased blood supply to brain, muscle, heart
4) decreased digestion and excretion
Which endocrine organ secretes insulin and glucagon?
The pancreas secretes insulin and glucagon
How does glucagon affect blood glucose levels?
Glucagon increases blood glucose levels
***opposite effect of insulin, which lowers blood glucose levels.
How does insulin affect blood glucose levels?
Insulin decreases blood glucose levels
T/F: Too much insulin causes hypoglycemia
True
What is the function of somatostatin?
Somatostatin inhibits both glucagon and insulin secretion
T/F: the testes secrete testosterone
True
Which 2 hormones are secreted by the ovaries?
Estrogen and Progesterone
What are the 4 phases of the menstrual cycle?
The 4 phases of the menstrual cycle are:
1) follicular phase
2) ovulation
3) luteal phase
4) menstruation
What is the corpus luteum?
The corpus luteum develops from a rupture follicle in the ovary and secretes estrogen and progesterone
T/F: the pineal gland secretes melatonin
True
How do peptide hormones act on their target cells?
Peptide hormones bind to receptors on the cell membrane, thereby initiating a chain of reactions inside the cell (secondary messengers)
How do steroid hormones act on their target cells?
Steroid hormones pass through the cell membrane and act directly inside the cell
T/F: Amino-acid-derived hormones act on their target cells directly
False, some amino-acid-derived hormones act on their target cells directly, while others behave as peptide hormones and use messengers
What is the function of a dendrite?
A dendrite conducts nerve impulses towards the cell body
What is the function of an axon?
An axon conducts nerve impulses away from the cell body.
**A xon is A way from cell body
What is the composition of a myelin sheath?
In the CNS, myelin is composed of the membranes of oligodendrocytes.
In the PNS, myelin is composed of the membranes of the Schwann cells.
What protein complex is responsible for the resting potential (-70 mV) of a neuron?
The Na+ - K+ pump is responsible for the neuron’s resting potential
T/F: In a resting neuron, Na+ concentration is higher inside the cell than outside the cell
False, Na+ concentration is higher outside a resting neuron
Do Na+ ions rush into or out of the cell during depolarization?
Na+ ions rush into a cell during depolarization
Do K+ ions rush into or out of the cell during repolarization?
During repolarization, K+ ions rush out of the cell
T/F: A neuron can conduct during the refractory period.
False, the neuron is unable to respond to stimulus during the refractory period
What is hyperpolarization?
Hyperpolarization refers to a state where the potential across the membrane is more negative than the resting potential
What is saltatory conduction?
Saltatory conduction is the “jumping” of an action potential between the unmyelinated Nodes of Ranvier
What happens when an action potential reaches a synapse (in a mammal)?
When an action potential reaches a synapse, the electrical signal causes the release of neurotransmitters from the presynaptic membrane into the synapse
What is the function of a sensory (afferent) neuron?
A sensory neuron carries impulses from sensory organs to the brain and spinal cord
What is the function of a motor (efferent) neuron?
A motor neuron transmits impulses from the brain and spinal cord to muscles or glands
Which type of neuron serves as a link between motor and sensory neurons?
Interneurons (associate neurons) link sensory and motor neurons
What are the two major subsystems of the nervous system?
The two major subsystems of the nervous system are the central nervous system and the peripheral nervous system
What are the components of the central nervous system?
Brain and spinal cord
T/F: Gray matter is composed of axons and white matter is composed of cell bodies
False, gray matter is composed of cell bodies and white matter is composed of axons
What is the largest part of the human brain?
The cerebral cortex is the largest part of the human brain
What is the function of the cerebral cortex?
The cerebral cortex processes and integrates sensory input and motor response, and controls memory
What is the function of the hypothalamus?
The hypothalamus is responsible for visceral functions such as hunger, thirst and sex drive
T/F: the cerebral cortex is the relay center for visual and auditory impulses
False, the midbrain is the relay center for visual and auditory impulses
What are the components of the hindbrain?
The hindbrain is composed of the:
1) cerebellum
2) pons
3) medulla oblongata
What is the function of the cerebellum?
The cerebellum is responsible for coordination
What part of the brain controls autonomic activities?
The medulla oblongata controls autonomic activities
What are the 4 regions of the spinal cord?
The 4 regions of the spinal cord are:
1) cervical
2) thoracic
3) lumbar
4) sacral
T/F: Dorsal root ganglia house the cell bodies of sensory root fibers
True
T/F: Sensory nerves enter the spinal cord ventrally and motor nerves leave the spinal cord dorsally
False, sensory nerves enter dorsally and motor nerves leave ventrally
Illustrate the hierarchy of the divisions of the peripheral nervous system
PNS
Sensory Motor
somatic automatic
parasympathetic sympathetic
What is the difference between a polysynaptic and monosynaptic reflex?
A monosynaptic reflex involves only one sensory neuron and one motor neuron.
A polysynaptic reflex involves one or more interneurons, in addition to a sensory neuron and a motor neuron
Which part of the nervous system readies the body for “fight or flight”?
The sympathetic nervous system readies the body for “fight or flight”
What is the function of the parasympathetic division of the nervous system?
The parasympathetic division opposes the sympathetic division by slowing the body down and conserving energy
Which division of the nervous system inhibits digestion?
The sympathetic division inhibits digestion
Which type of photoreceptor cell is specialized for color vision? Which type is specialized for low light conditions?
Cones are for Color.
Rods are for night vision
What is the fovea?
The fovea is the region of the retina with a high density of CONES
What are the components of the middle ear?
The middle ear is composed of the :
1) tympanic membrane
2) malleus
3) incus
4) stapes
What are the components of the inner ear?
The inner ear is composed of the cochlea (which contains the Organ of Corti) and the semicircular canals
What are alleles?
Alleles are different forms of the same gene. Alleles occupy the same position on homologous chromosomes
Define genotype
Genotype refers to the genetic makeup of an individual
Define phenotype
Phenotype refers to the Physical manifestation of an individual’s genotype
Define homozygous
Homozygous individuals have two copies of the same allele for a given trait
Define heterozygous
Heterozygous individuals have two different alleles for a given trait
Summarize Mendel’s First Law (Law of Segregation)
Mendel’s first law states that alleles segregate during meiosis; specifically:
1) Genes exist in alternative forms (alleles)
2) An individual inherits two alleles for each trait, one from each parent
3) the two alleles segregate during meiosis
4) If two different alleles are present, only one will be fully expressed
Summarize Mendel’s Second Law (Law of Independent Assortment)
Mendel’s second law states that alleles of unlinked genes assort independently during meiosis
If P= dominant (purple) and p=recessive (white)
What would be the phenotypic ration of a PP x pp cross?
100% purple
If P= dominant (purple) and p=recessive (white)
What would be the phenotypic ratio of a Pp x Pp cross
75% purple : 25% white
If P= dominant (purple) and p=recessive (white)
What would be the phenotypic ratio of a Pp x pp cross
50% purple : 50% white
If P= dominant (purple) and p=recessive (white)
What would be the genotypic ratio of a Pp x pp cross
50% Pp : 50% pp
If P= dominant (purple) and p=recessive (white)
What would be the genotypic ratio of a Pp x Pp cross?
25%PP : 50%Pp : 25%pp
T/F: Recombinant frequencies are roughly additive
True
Given: X and Y recombinant frequency = 5%
X and Z recombinant frequency = 13%
What is the Y and Z recombinant frequency if the gene order is XYZ?
8%
Given: X and Y recombinant frequency = 5%
X and Z recombinant frequency = 13%
What is the Y and Z recombinant frequency if the gene order is YXZ?
18%
What is a map unit
1 map unit = 1% recombinant frequency
Red flowers crossed with white flowers yield pink flowers. What kind of dominance is portrayed in this example?
Incomplete dominance
Assuming codominance, what happens to the phenotype in the presence of two dominant alleles?
The phenotype of each allele is simultaneously displayed (e.g. type AB blood)
What is penetrance of a genotype?
The penetrance of a genotype is the percentage of individuals in a population who actually express its phenotype
What is expressivity of a genotype?
The expressivity of a genotype is the degree to which the phenotype is expressed in an individual
T/F: In humans, most sex-linked genes are located on the Y chromosome
False, most sex-linked genes are on the X chromosome
What percentage of daughters will inherit their father’s sex linked gene?
100% of daughters will inherit their father’s sex-linked gene
What percentage of sons will inherit their father’s sex-linked gene?
0% of sons will inherit their father’s sex-linked gene
What percentage of sons will inherit their mother’s sex-linked gene (assuming a heterozygous mother)?
50% of sons will inherit their mother’s sex-linked genes
T/F: Females can express a sex-linked recessive trait
True, a female carrier and a male with the recessive trait will have a 25% chance of giving birth to a female child with the recessive trait
What is nondisjunction?
Nondisjunction is the failure of homologous chromosomes (or sister chromatids) to separate properly during cellular reproduction
What are the three different results of chromosomal breakage?
1) DUPLICATION: the fragment joines with its homologous chromosome
TRANSLOCATION: the fragment joins with a non-homologous chromosome
INVERSION: the fragment rejoins its original chromosome but in the reverse position
Name the 4 nitrogenous bases in DNA
Adenine
Cytosine
Guanine
Thymine
Name the purines and pyrimidines
PURe AS GOLD
purines = adenine and guanine
pyrimidines= cytosine, thymine, uracil
What is the base-pairing in DNA? How many bonds hold the bases together?
Cytosine — Guanine (3 Hydrogen bonds)
Adenine – Thymine (2 hydrogen bonds)
Name three differences between RNA and DNA
RNA uses ribose instead of deoxyribose.
RNA replaces thymine with uracil
RNA is usually single-stranded
T/F: DNA synthesis proceeds in the 3’ to 5’ direction
False, DNA synthesis proceeds in the 5’ to 3’ direction
What are the four types of RNA and what are their functions?
1) Messenger RNA (mRNA)= contains codons for peptide chain synthesis
2) Transfer RNA (tRNA) = transports amino acids to the ribosome during protein synthesis
3) Ribosomal RNA (rRNA) = structural component of ribosomes
4) Heterogeneous nuclear RNA (hnRNA)= precursor of mRNA
What is transcription?
Transcription is the process whereby mRNA is synthesized from a DNA template
What is translation?
Translation is the process whereby proteins are synthesized from a mRNA template
What is an exon? What is an intron?
An exon is a coding sequence on a gene
An intron is a non-coding sequence on a gene
What is a codon?
A codon is a 3-base sequence on mRNA that codes for a specific amino acid
What is an anticodon?
An anticodon is a 3-base sequence on tRNA that is complementary to a mRNA codon
What are the 3 stages of polypeptide sythesis?
The 3 stages of polypeptide synthesis are:
1) initiation
2) elongation
3) termination
What are the 3 types of base pair mutations that can occur during protein synthesis?
Types of base pair mutations are:
substitutions
insertions
deletions
T/F: A frameshift mutation usually leads to a non-functioning protein
True
What types of nucleic acid can be found in a virus?
A virus can contain DNA or RNA
What is a retrovirus?
A retrovirus is an RNA virus that codes for the enzyme reverse transcriptase, which uses the RNA as a template for DNA synthesis
What is a prophage (provirus)?
A prophage is a virus that has integrated its DNA into the host cell’s DNA
What is a bacteriophage?
A bacteriophage is a virus that attacks only bacteria
Describe the lytic and lysogenic cycles
Bacteriophage infection results in either a lytic or a lysogenic cycle.
lytic cycle= results in the production of new progeny that cause the cell to burst (lyse).
lysogenic cycle= results in incorporation of the viral DNA into the bacterial DNA where it remains inactive.
A lysogenic cycle may progress to a lytic cycle.
What are the three mechanisms by which bacteria can increase genetic variability?
TRANSFORMATION: incorporation of foreign chromosome fragments
CONJUGATION: transfer of genetic material between two bacteria
TRANSDUCTION: virus carries DNA between two bacteria
What is an operon?
An operon is a gene that regulates (bacterial) transcription.
What is an inducible system?
An inducible system requires the presence of an inducer for transcription to occur
What is a repressible system?
A repressible system is in a constant state of transcription unless a corepressor is present to inhibit transcription
Define fitness according to Darwin
Fitness is the ability of an organism to mate and produce fertile offspring
Describe the model of punctuated equilibrium
the model of punctuated equilibrium holds that evolution is characterized by long periods of stasis punctuated by rapid evolutionary changes
What are homologous structures?
Homologous structures are similar in structure and origin but not function (e.g. whale flippers/human arms)
What are analogous structures?
Analogous structures are similar in function but not in origin (e.g. insect wings/bird wings)
THINK: “A” open at the bottom because came from different origins, but then converge –> similar in function
What are vestigial structures?
A vestigial structure is a remnant structure that has lost its ancestral function (e.g. tail bone in man).
What are the 5 necessary conditions for the Hardy-Weinberg equation to hold true?
- There are NO mutations that affect the gene pool
- The population must be very LARGE
- Genes in a population are equally successful at reproducing
- Mating occurs randomly
- There is no net migration of individuals into or out of the population
How does genetic drift differ from gene flow?
Genetic drift refers to changes in the gene pool due to CHANCE. Gene flow refers to the changing of the gene pool due to the migration of individuals
T/F: Stabilizing selection maintains a well adapted uniform character in a population
True
How does disruptive selection affect the phenotype of a population?
Disruptive selection favors the phenotypical extremes, leading to the expression of two or more phenotypic forms
How does directional selection affect the phenotype of a population?
Directional selection favors the expression of one phenotypical extreme.
When are two populations descending from the same ancestral stock considered to be different species?
Two populations are considered to be different species when they can no longer interbreed and produce viable offspring
What is adaptive radiation?
Adaptive radiation is the emergence of a number of distinct lineages from a single ancestral species. The different lineages usually result when a group begins to exploit a different niche
Describe convergent evolution
Convergent evolution refers to the independent development of similar characteristics by non-related groups
Describe parallel evolution
Parallel evolution refers to the process whereby related groups independently develop similar characteristics due to analogous environmental pressures
Describe divergent evolution
Divergent evolution refers to the process whereby related groups independently develop dissimilar characteristics
What is autoradiography?
can be used to label amino acids with radioactive molecules. uses radioactive molecules to trace and identify cell structures, and localize biochemical activity.
T/F: A substrate is changed during an enzymatic reaction.
TRUE!! remember: an enzyme is NOT changed by reaction that it catalyzes.
Crossing over occurs in ___________
Meiosis, prophase I
Where does post-transcriptional processing occur?
IN THE NUCLEUS!
Yeast are:
1) eukaryotic
2) unicellular
3) facultative anaerobes
Acetylcholine is a ____________ used by the ___________nervous system…particularly the __________ innervating the heart. What are its main effects?
neurotransmitter used by the PARASYMPATHETIC ns …vagus nerve innervating the heart.
Effects:
1) stimulates the opening of K+ channels…thus inhibits depolarization
2) increases the time between heartbeats.
Na+ voltage gated channels contribute to the _________ but not the__________.
Na+ voltage gated channels only contribute to the ACTION POTENTIAL….not the resting potential.
**Na+ channels are only open during the action potential …if they’re removed, the resting potential would not be affected.
Which channels are more sensitive to a change in membrane potential - Na+ or K+ channels?
Na+ voltage-gated channels are more sensitive - that’s why they open first!
Which channels are more sensitive to a change in membrane potential - Na+ or K+ channels?
Na+ voltage-gated channels are more sensitive - that’s why they open first!
