Unit 3

Digestive System

Q. Identify and give a function for each of the following: mouth, tongue, teeth, salivary glands, pharynx, epiglottis, cardiac sphincter, stomach, pyloric sphincter, duodenum, liver, gall bladder, pancreas, small intestine, appendix, large intestine (colon), rectum, anus.
A. The mouth receives food and is where digestion starts. The tongue has several muscles and it moves food around the mouth. Salivary glands produce saliva and squirt it into the mouth. They also produce salivary amylase which digests carbohydrates. The pharynx is at the back of the throat and assists in swallowing the food. The epiglottis is a flap that covers the trachea to prevent choking. The cardiac sphincter is a ring of muscle at the entrance to the stomach and prevents the contents of the stomach from splashing up into the esophagus. The stomach is a chamber that stores food and produces HCL acid, mucus, and pepsin. The acid breaks down food and turns it into chyme, the mucus protects the stomach wall from the acid, and the pepsin digests proteins into polypeptides. The pyloric sphincter is at the bottom of the stomach and squirts chyme into the duodenum. The duodenum is the first 25 cm of the small intestine and is where the digestion occurs in the small intestine. The liver is a large gland that has many functions, such as making bile that emulsifies fat. The gall bladder is a small organ that stores bile. The pancreas is a gland that produces many enzymes that aid in digestion of fats, proteins, and carbohydrates in the duodenum. The small intestine is a 6 meter long organ that digests chyme and absorbs nutrients. The appendix is a small organ attached to the large intestine. It doesn't really do much, but it can get inflamed, burst, lead to an infection called peritonitis that can kill you. The large intestine is a 1.5 meter long organ that absorbs water and compacts the remaining matter into feces. The rectum is the last 20 cm of the large intestine that moves feces to the anus. The anus is at the end of the large intestine and expels feces out of the body.  

Q. Describe swallowing and peristalsis.
A. In swallowing, the tongue moves food to the back of the mouth and into the pharynx which leads to the esophagus. Peristalsis pushes food along the esophagus and into the stomach through muscle contractions.

Q. List at least six major functions of the liver.
A. The liver produces bile, receives blood, processes proteins, fats, and carbohydrates, controls release of these back into the circulation system, detoxifies blood, and produces cholesterol.

Q. Explain the role of bile in the in the emulsification of fats.
A. Bile has acids that break down fats into tiny droplets, making it easier for them to be digested.

Q. Describe how the small intestine is specialized for chemical and physical digestion and absorption.
A. Bile breaks down fats with acids and enzymes break down other things like proteins and carbohydrates. Villi on the intestinal wall absorb nutrients.

Q. Describe the structure of the villus, including microvilli, and explain the functions of the capillaries and lacteals within it.
A. Villi are small projections that look almost like fingers. They are covered in thousands of even smaller microvilli. Microvilli have intestinal enzymes called brush-border enzymes. They greatly increase the surface area of the small intestine which allows it to absorb more nutrients. Capilleries carry sugars and amino acids, and lacteals carry glycerol and fatty acids that have been packed into lipoprotein droplets by epithelial cells.

Q. Relate the following digestive enzymes to their glandular sources and describe the digestive reactions they promote.  Salivary amylase, Pancreatic amylase, proteases (pepsin, trypsin, pepsinogen), lipase, peptidase, maltase, nuclease.
A. Salivary amylase is produced in salivary glands in the mouth and digest carbohydrates. Pancreatic amylase is produced by the pancreas and digest fats, proteins, carbohyrates, and nucleic acids. Pepsinogen turns into pepsin and produced by gastric glands. Pepsin breaks proteins into polypeptides. Trypsin is made in the pancreas and turns proteins into peptides.  Lipase is made in the pancreas turns triglycerides into glycerol and  fatty acids. Peptidase is produced by the small intestine and turns peptides into amino acids. Maltase is made in the small intestine and turns maltose into glucose. Nuclease is produced by the pancreas and turns nucleic acids into nucleotides.

Q. Describe the role of water as a component of digestive juices.
A. Water is part of salivary amylase which digests carbohydrates.

Q. Describe the role of sodium bicarbonate in pancreatic juice.
A. Sodium bicarbonate is slightly basic and it is used in pancreatic juice to neutralize chyme, which is acidic.

Q. Describe the role of hydrochloric acid in gastric juice.
A. HCL kills most bacteria, breaks down connective tissues of meat and activates pepsin.

Q. Describe the role of mucus in gastric juice.
A. Mucus is made by goblet cells in the stomach lining and protect it from being damaged by the HCL in the stomach. Ulcers (an open sore) appears if the HCL begins to break down the stomach wall.

Q. Describe the importance of the pH level in various regions of the digestive track.
A. The mouth and esophagus have a neutral pH because they have no protection, and the mouth uses mechanical digestion instead of chemical. The stomach has a acidic pH to break down meat and kill bacteria and activate pepsin. The stomach is protected by mucus. The small intestine is basic because the acidic chyme from the stomach has to be neutralized.

Reproductive System


Q. Identify and give functions for each of the following: Testes, Seminiferous tubules and Interstitial Cells, Epididymis, Ductus (Vas) Deferens, Prostate Gland, Cowper's Gland, Seminal Vesicles, Penis and Urethra.
A. The Testes are in the scrotum and produce sperm. Seminiferous tubules are tubes in the testes in which the sperm are produced. Interstitial cells are between the S tubules and produce testosterone. The Epididymis is a tube in which the sperm are stored. The Vas Deferens is a tube that stores sperm and transports them out of the testes. The Prostate gland is a gland that secretes a fluid onto the sperm that is basic to neutralize the acidic urethra and vagina. The Cowper's gland is a gland that lubricates sperm. The Seminal Vesicles secrete fructose which the sperm use as an energy source. The Penis is an organ that transports sperm into the vagina through the urethra. The Urethra is a tube in the penis that used to transport both semen and urine out of the body.

Q. Demonstrate a knowledge of the path of sperm from the seminiferous tubules to the urethral opening.
A. Once sperm are fully formed, they leave the seminiferous tubules and go to the epididymis to mature. Then they go into the vas deferens which takes them by the seminal vesicles that supply them with fructose for energy. Then they enter the urethra and go through the prostate gland which gives them a basic coating to protect them from the acidic urethra and vagina. Lastly the sperm are lubricated by the cowper's gland before they exit the body through the urethra.

Q. List the functions of Seminal Fluids.
A. Seminal fluids protect sperm from acid, lubricate sperm, and nourish sperm.

Q. Identify the tail, midpiece, head, and acrosome of a mature sperm and state their functions.
A. The tail is a flagella that propels the sperm. The midpiece is the middle of the sperm and contains mitochondria that provides ATP (energy) for the sperm. The head is the front of the sperm and contains the sperms DNA. The acrosome is a lysosome that uses digestive enzymes to get through the outer layers of an egg.

Q. Describe the functions of testosterone.
A. Testosterone is necessary for the development of sperm, it causes puberty in males, it can cause aggressive behaviour. Secondary sex characteristics caused by it are: deepening of the voice, adam's apple, development of muscles, increase in height, and growth of hair such as pubic hair.

Q. Demonstrate a knowledge of the control of testosterone levels by the endocrine system.
A. The hypothalamus releases GnHR (gonadotropin releasing hormone) which targets the anterior pituitary gland that secretes LH (luteinizing hormone) and FSH (follicle stimulating hormone). LH in males targets the interstitial cells in the testes and increases testosterone production. Less LH results in less testosterone.

Q. Identify and give a function for each of the following: Ovaries, Follicles and Corpus Luteum, Oviducts, Uterus, Cervix, Vagina, Clitoris.
A. The Ovaries are the main female sex organ and are the site of egg and hormone production. Follicles are cells that contain an egg and rupture during ovulation to release the egg from the ovary. The Corpus Luteum is the remains of the follicle and produce hormones. The Oviducts are tubes that propel the egg toward the uterus. The Uterus is the place where a fertilized egg implants and develops into a fetus. The Cervix is the entrance to the uterus and holds the baby in the uterus. The Vagina is the birth canal and where the penis deposits sperm. The Clitoris is similar to the penis in that it has erectile tissue and many nerve endings.

Q. Describe the functions of estrogen.
A. It causes the thickening of the endometrium . Secondary sex characteristics are: pubic and armpit hair, body fat distributed to the breasts and hips, and breast development.

Q. Describe the sequence of events in the ovarian and uterine cycles.
A. The Ovarian cycle starts with the Follicular Phase. The anterior pituitary gland releases FSH which causes the follicle to develop. Then follicle starts producing estrogen and some progesterone. On day 14 the follicle is fully developed, the egg is mature, and a surge in LH resulting in ovulation. The egg breaks out of the follicle and enters the oviduct. The Uterine cycle has 3 phases: the menstrual phase, the proliferation phase, and the secretory phase. In the menstrual phase the endometrium breaks down and is discharged. It is caused by decreased amounts of estrogen and progesterone. Occurs during days 1-5. In the proliferation phase the endometrium rebuilds and thickens. This is caused by the developing follicle. Occurs during days 6-14. In the secretory phase, the endometrium doubles in thickness and mucus is secreted. This is caused by increased production of progesterone by the corpus luteum.

Q. Demonstrate knowledge of the ovarian and uterine cycles by hormones.
A. The Ovarian cycle is controlled by the release of FSH and LH. The follicle also produces estrogen and progesterone. The Uterine cycle is controlled by estrogen and progesterone produced by the ovary.

Q. Demonstrate knowledge of a positive feedback mechanism involving Oxytocin.
A. Oxytocin is made in the hypothalamus and controls uterine contractions. Contractions cause the hypothalamus to make more oxytocin, which causes more contractions.

Q. Describe the hormonal changes that occur as a result of implantation.
A. When hormones are artificially put into the body, it causes the body to greatly decrease the amount of that hormone it produces.

Digestion Question

Q. What are teeth made of?

A. Teeth have lots of calcium in them and are made of four parts: enamel, dentin, pulp, and cementum.
Enamel is the white top of the tooth and is the hardest part of your body. The dentin is a bone like under the enamel that contains some nerves. The pulp contains blood vessels and nerves at the center of the tooth. The cementum covers the root of tooth and attaches it to the jaw.

Unit 2

Protein Synthesis


Q. Demonstrate a knowledge of the basic steps of protein synthesis, identifying the roles of DNA,  mRNA, tRNA, and ribosomes in the processes of transcription and translation.
A. In transcription, DNA unwinds and a strand of RNA matches up its nucleotides with it. Then the DNA winds back up and a strand of mRNA leaves the nucleus and heads toward a ribosome. In translation, mRNA attaches to a ribosome. The ribosome reads the mRNA. Then tRNA matches its anti-codon to the mRNA's codon (group of three bases and code for specific amino acid). tRNA has a amino acid attached to it, and when it is matched with a codon, a peptide bond forms between the amino acids. The empty tRNA then leaves the ribosome and the amino acids bond to form a protein.

Q. Determine the sequences of amino acids coded for by a specific DNA sequence, given a table of mRNA codons.
A. AUG- Methionine, START , GUC- Valine, UAU- Tyrosine, UGA- STOP.

Q. Give examples of 2 environmental mutagens that can cause mutation in humans.
A. Ultraviolet light and gamma radiation.

Q. Use examples to explain how mutations in DNA affect protein synthesis and may lead to genetic disorders.
A. A mutation can cause amino acids to be changed. For example, one amino acid changed in a hemoglobin in the blood, glutamic acid being changed to valine, causes sickle shaped blood cells to develop. Other mutations are deletion and insertion mutations. In deletion a amino acid is deleted and in insertion a amino acid is added. Both result in the gene becoming unreadable.

Transport Across Cell Membrane


Q. Apply knowledge of organic molecules to explain the structure and function of the fluid mosaic membrane model.
A. The fluid mosaic membrane model is made up of several parts: a phospholipid bilayer which makes up most of the membrane and protects the intracellular fluids from the extracellular fluids, glycolipids are phospholipids attached to carbohydrate chains and act as self recognition markers for the cell, cholesterol is a lipid in the membrane that serves to make the bilayer more flexible and less fluid, receptor proteins that trigger a cellular response when it detects certain molecules, recognition proteins have an attached carbohydrate chain and act as identification tags, transport proteins control the movement of water soluble molecules through the membrane, channel proteins allow water-soluble molecules to pass through the membrane, and carrier proteins use ATP to move molecules across the membrane.

Q. Explain why the cell membrane is described as "selectively-permeable".
A. It will only allow certain molecules to pass through it.

Q. Compare and contrast the following: diffusion, facilitated transport, osmosis, active tranport.
A. Diffusion is movement of water solute molecules across the membrane from high to low concentrations. Facilitated transport is transport that uses channel proteins to move molecules from high to low concentrations. Osmosis the movement of water molecules across the membrane. Active transport is transport that uses energy (ATP) to move molecules from low to high concentrations.    

Q. Explain factors that affect the rate of diffusion across a cell membrane.
A. The size of the molecule (smaller molecules diffuse faster). Temperature (higher temperatures increase the rate of diffusion). The concentration gradient (greater difference in concentration makes molecules diffuse faster). The number of pores or carrier proteins in the cell membrane can also increase the rate of diffusion.

Q. Describe endocytosis, including phagocytosis and pinocytosis, and contrast it with exocytosis.
A. Endocytosis is the process of bringing particles into the cell that are too large for carrier proteins. The cell membrane folds in and then pinches off to form a vesicle in the cell that contains the particles. It then undergoes the process of  phagocytosis or pinocytosis. In phagocytosis, the particles in the vesicle are digested. In pinocytosis, nutrients are taken into the cell. The opposite of endocytosis is exocytosis. Exocytosis is the process of taking waste out of the cell by merging a vesicle filled with waste with the cell membrane, thus emptying its contents outside of the cell.

Q. Predict the effects of hypertonic, isotonic, and hypotonic environments on animal cells.
A. In a hypertonic environment, water would move out of the cell, causing it to shrink (crenation). In a isotonic environment, there is no change in the cell. In a hypotonic environment, water would move into the cell, causing it to expand or burst (lysis).

Q. Demonstrate an understanding of the relationships and significance of surface area to volume, with respect to cell size.
A. Small cells have a high surface area to volume ratio. This allows diffusion and osmosis to work faster.
Larger cells have a smaller surface area to volume ratio than small cells. This slows down diffusion and osmosis relative to its size.

Enzymes


Q. Demonstrate an  understanding of the following terms: metabolism, enzymes, substrate, coenzymes, activation energy.
A. Metabolism is all of the chemical processes in a cell. Enzymes are proteins that catalyze a chemical reaction. One enzyme catalyzes one reaction. A substrate attaches to an enzyme's active site and they combine to form a enzyme-substrate complex. Coenzymes work with the enzyme to complete the active site. Activation energy is the energy that is used to start a reaction.

Q. Identify the source gland for thyroxin  and relate the function of thyroxin to metabolism.
A. Thyroxin comes from the thyroid gland. Thyroxin promotes growth and increases metabolism.

Q. Explain the lock and key model of emzymatic action.
A. The enzyme and substrate fit together perfectly without having to change shape.

Q. Explain the role of vitamins in biochemical reactions.
A. Vitamins are used by enzymes to use energy during reactions.

Q. Differentiate between the roles of enzymes and coenzymes in biochemical reactions.
A. An enzyme catalyzes reactions ( speeds them up) and a coenzyme works with the enzyme by completing the active site so the reactions may occur.

Q. Apply knowledge of proteins to explain the effects on enzyme activity of pH, temperature, substrate concentration, enzyme concentration, competitive inhibitors, and heavy metals.
A. A very high or very low pH makes it very difficult, even impossible for an enzyme to function. So enzymes need a pH between 6 and 8 to work. Very high and very low temperatures also lower an enzymes effectiveness, a human's body temperature is about 37 degrees celsius which is the optimal temperature for our enzymes. High substrate concentrations will increase the reaction rates and low concentrations will lower the reaction rate. High enzyme concentrations will increase the reaction rate and low concentrations will lower the reaction rate. Competitive inhibitors completely prevent an enzyme from making any reactions while they are bound to the active site (can bind irreversibly). Heavy metals denature enzymes and bind irreversibly.