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Semmelweis Entrance Exam Medicine
Biology
What are carbohydrates and lipids? - ANS Organic compounds that are mostly composed of three types of atom; carbon, hydrogen and oxygen What do carbohydrates do? - ANS provide energy, in the form of sugars like glucose and fructose, but they also make up structures like cellulose, which form the cell wall of plant cells What type of carbohydrate is the most important source of energy? - ANS mono-, di- and poly- saccharides What are mono and disaccharides? - ANS polar and soluble in water What are polysaccharides? - ANS Macromolecules resulting from polymerisation (condensation) of sugars and are not soluble in water Examples of monosaccharides - ANS ribose, glucose, fructose, galactose What forms a disaccharide? - ANS two monosaccharides linked together by condensation reactions with glycosidic bonds releasing one H2O molecule Alpha glucose structure - ANS Beta glucose structure - ANS Examples of Polysaccharides - ANS cellulose, glycogen and starch
Monomer of Sucrose - ANS glucose and fructose monomer of maltose - ANS glucose and glucose monomer of lactose - ANS glucose and galactose monomer of starch - ANS glucose monomer of glycogen - ANS glucose monomer of cellulose - ANS glucose In animals, what carbohydrate stores energy? - ANS glycogen What jobs do carbohydrates have other than storing energy? - ANS structural components What differs the polysaccharides all made up of glucose? - ANS they differ in the arrangement of glucose molecules and position of the glycosidic bonds Starch arrangement - ANS amylopectin branched, amylose linear What is galactose? - ANS a sugar in milk What is fructose? - ANS a sugar found in fruit and honey Main characteristic of lipids? - ANS little to no affinity to water, mostly hydrophobic
What is the tertiary protein structure? - ANS three dimensional conformation. Forms when a polypeptide folds up after tr ANS lation. Stabilized by intramolecular bonds between amino acids and polypeptides What is the quaternary protein structure? - ANS linking two or more polypeptides to form a single protein What is the basic structure of DNA? - ANS it is composed of three parts, a pentose sugar, a phosphate group and a nitrogenous base Difference in structure between DNA and RNA - ANS RNA contains a ribose sugar instead of deoxyribose and is also single stranded as well as having Uracil as a base instead of thymine What are the two double helix strands held together by? - ANS hydrogen bonds What are hydrogen bonds? - ANS a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom Why is DNA antiparallel? - ANS so that the paired bases can face each other what is mRNA? - ANS Messenger RNA: Encodes amino acid sequence of a polypeptide What is tRNA? - ANS tr ANS fer RNA. It carries amino acids around during tr ANS lation. What is rRNA? - ANS Ribosomal RNA. with ribosomal proteins, makes up the ribosomes, the organelles that tr ANS late the mRNA
what is snRNA? - ANS small nuclear RNA. with proteins, forms complexes that are used in RNA processing in eukaryotes What are enzymes? - ANS biological catalysts. They are globular proteins that can speed up a biochemical reaction. Alternative pathway What is glycolysis? - ANS the breakdown of glucose by enzymes, releasing energy and pyruvic acid. What is the kreb's cycle? - ANS second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions What is the mechanism of ATP production in the mitochondria? - ANS located in the inner mitochondrial membrane, allows the protons to diffuse back across the membrane to the matrix. ATP synthase uses the energy that the protons release as they diffuse down the concentration gradient to produce ATP What is the net yield of ATP in cellular respiration? - ANS 38 total 2 in glycolysis 2 in Krebs's cycle 34 in chemiosmosis (electron tr ANS port chain) What is DNA replication? - ANS the process of copying DNA What is DNA tr ANS cription? - ANS the organic process whereby the DNA sequence in a gene is copied into mRNA What is tr ANS lation? - ANS the decoding of an mRNA message into amino acids which ultimately form protein
Cell membrane diagram - ANS Describe the process of mitosis - ANS - Start with: Diploid, 2N
- Interphase: DNA replication = Dipoid, 4N
- Prophase: Condensation of chromatin, appearance of sister chromatids
- Metaphase: Sister chromatids align
- Anaphase: Sister chromatids separate, centromeres divide
- Telophase and Cytokinesis: Two identical, diploid, daughter cells: Diploid, 2N Describe the process of meiosis - ANS When a cell divides to form gametes:
- Copies of the genetic information are made
- The cell divides twice to form four gametes, each with a single set of chromosomes
- All gametes are genetically different from each other Gametes join at fertilisation to restore the normal number of chromosomes. The new cell divides by mitosis. The number of cells increases. As the embryo develops, cells differentiate. When does crossing over occur? - ANS prophase I of meiosis When does recombination occur in meiosis? - ANS during prophase I, when homologous chromosomes line up in pairs and swap segments of DNA.
What is the structure of prokaryotic cells? - ANS Example of prokaryotic cell - ANS E. coli Example of eukaryotic cell - ANS plant and animal cells What is the structure of eukaryotic cells? - ANS What is the structure of a virus? - ANS A typical virus is composed of a core of DNA or RNA surrounded by a protein coat What is tr ANS formation? - ANS uptake of DNA from environment What is conjugation? - ANS A process in which 2 organisms exchange genetic material What are all the parts to the digestive system? - ANS How does absorption occur? - ANS diffusion, facilitated diffusion, osmosis, active tr ANS port How does absorption work? - ANS - food molecules are absorbed into the blood or the lymph. To be absorbed in the body the molecules need to pass into the capillaries or the villus. Fats absorb into the lymph
- Substances to be absorbed move from the lumen into the epithelial villi
- Amino acids and monosaccharides move from the villi into capillaries and monoglycerides move into the lacteals What are some of the digestive enzymes? - ANS -typsinogen and chymotrypsin (breaks down proteins)
What is the process of cellular immune response? - ANS the immune system's third line of defense, involving the attack of pathogens by T cells What are the three lines of defense? - ANS First line: Natural barriers: Skin and mucous membranes Second line: Inflammation Third line: Adaptive (acquired) immunity How does blood clotting occur? - ANS Clotting seals damaged vessels to prevent pathogenic entry
- Injured cells and platelets release clotting factors
- These factors convert prothrombin into thrombin
- Thrombin converts fibrinogen (soluble) into fibrin (insoluble)
- Fibrin forms a mesh of fibres that block the injured site - Clotting factors also cause platelets to become sticky and form a solid plug (called a clot), sealing the wound - This process of events is called a coagulation cascade
- Clot formation in coronary arteries lead to heart attacks What is innate immunity? - ANS Nonspecific protection against foreign substances indiscriminantly All cells but lymphocytes What is the humoral immune response? - ANS The humoral immune response targets pathogens circulating in "humors," or extracellular fluids, such as blood and lymph. Antibodies target invading pathogens for destruction via multiple defense mechanisms, including neutralization, opsonization, and activation of the complement system. Patients that are impaired in the production of antibodies suffer from severe and frequent infections by common pathogens and unusual pathogens What are muscles? - ANS tissues or fibers that cause movement of body parts and org ANS
Structure of muscles - ANS each muscle fiber contains many microfibrils each divided along its length into repeating units called sacromeres General definition of joints - ANS Areas where two or more bones join together Describe muscle contraction - ANS Muscle contraction Is caused by interactions of thick and thin filaments Thin filament (actin) is attached to Z line Thick filaments (myosin) is "hanging" in the middle When myosin attaches to actin it pulls strings of actin toward each other Parts of the male reproductive system - ANS Parts of the female reproductive system - ANS Describe the ovarian cycle - ANS Eggs are formed through meiosis in ovaries 1 matures enough to be released into fallopian tubes (halfway through monthly cycle) Corpus luteum where egg used to be disintegrates unless fertilized What causes ovulation? - ANS surge of LH What causes menstruation? - ANS drop in estrogen and progesterone
Explain the resting and action potential of nerves - ANS The resting potential tells about what happens when a neuron is at rest. An action potential occurs when a neuron sends information down an axon, away from the cell body. ... When the depolarization reaches about -55 mV a neuron will fire an action potential Explain the structure of the human eye - ANS What is the mechanism of vision? - ANS The light rays emitted by various objects are captured by eyes and then send inwards. The light rays are visible wavelength are focussed on the retina through the cornea & the lens. This generates the potentials (impulses) in the rods and the cones present in the retina How does the hearing mechanism work? - ANS Sound waves enter the outer ear and travel through the external auditory canal until they reach the tympanic membrane, causing the membrane and the attached chain of auditory ossicles to vibrate How does the olfactory system function? - ANS involves the detection and identification of molecules in the air. Once detected by sensory org ANS , nerve signals are sent to the brain where the signals are processed What are mendel's laws? - ANS 1. Law of Dominance
- Law of Segregation
- Law of Independent Assortment What is the overall structure of genes? - ANS Genes are composed of deoxyribonucleic acid (DNA), except in some viruses, which have genes consisting of a closely related compound called ribonucleic acid (RNA). A DNA molecule is composed of two chains of nucleotides that wind about each other to resemble a twisted ladder What is a gene? - ANS segment of DNA that codes for a protein
What are the levels of gene expression? - ANS Genes that code for amino acid sequences are known as 'structural genes'. The process of gene expression involves two main stages: Tr ANS cription: the production of messenger RNA (mRNA) by the enzyme RNA polymerase, and the processing of the resulting mRNA molecule What is a frameshift mutation? - ANS mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide. The resulting protein is nonfunctional What is a missense mutation? - ANS Point mutation in which a single nucleotide is changed, resulting in a codon that codes for a different amino acid. What is a nonsense mutation? - ANS change resulting in early stop codon What is a chromosomal mutation? - ANS A change in the number or structure of chromosomes What is down's syndrome caused by? - ANS trisomy 21 What is turner syndrome caused by? - ANS 45 chromosomes instead of 46 What is Klinefelter syndrome caused by? - ANS 47 chromosomes, three sex chromosomes, XXY What is edward's syndrome caused by? - ANS Trisomy 18 What is Patau syndrome caused by? - ANS Trisomy 13 What is dominant inheritance? - ANS one dominant allele is needed to show disease and dominant lethal alleles are usually eliminated from the population
-Hip (pelvic) girdle -Legs -Ankles -Feet What type of hormones enter their target cells? - ANS Being lipids, steroid hormones enter the cell by simple diffusion across the plasma membrane What type of muscle is the diaphragm? - ANS skeletal muscle Which vitamins are soluble in water? - ANS B and C What is pepsin? - ANS Enzyme that breaks down proteins in the stomach What is pepsin made of? - ANS short polypeptides linked together What is tubulin? - ANS Hollow tubes 25 nanometers in diameter What are centrioles? - ANS Centrioles help organize cell division and are formed from tubulin and located near the nucleus. What is triploidy? - ANS three sets of chromosomes What is monoploidy? - ANS missing a chromosome in a set of chromosomes What is aneuploidy? - ANS Abnormal number of chromosomes
What is a gonosome? - ANS synonym for sex chromosome What is autosomal? - ANS chromosomes that are not sex chromosomes What is connective tissue? - ANS Framework of the body, providing support and structure for the org ANS. What is included in connective tissue? - ANS Loose ordinary connective tissue Adipose tissue Blood and blood forming tissues Dense ordinary connective tissue Cartilage Bone What is the epithelium? - ANS A tissue that lines internal and external tissues in animals.
