mid session exam

Question 1

define anatomy

Answer 1

the scientific discipline that investigates the body’s structure

Question 2

define physciology

Answer 2

scientific investigation of the processes or functions of living things

Question 3

define the body’s levels of organisation

Answer 3

chemical level: interaction of atoms
cell level: functional unit of life
tissue level: group of similar cells and the materials surrounding them
organ level: one or more tissues functioning together
organ system level: group of organs functioning together

Question 4

list the organs systems and give a brief description of their functions

Answer 4

cell physiology: examines processes in cells
systemic physiology: function of organ systems
neurophysiology: focuses on the nervous system
cardiovascular: the heart and blood vessels

Question 5

define homeostasis and explain its importance, as well a variable and set point

Answer 5

homeostasis: the existence and maintenance of a relatively constant environment within the body
importance: maintains optimal conditions for enzyme action throughout the body and all cell functions.
values/variables fluctuate around the set point to establish a normal range of values
set point: the ideal normal value of a variable

Question 6

in the context of homeostasis, explain negative and positive feedback

Answer 6

negative feedback: any deviation from the set point is made smaller (resisted), e.g. regulation of blood pressure, body temperature, blood sugar levels
positive feedback: when a deviation occurs, the response is to make the deviation greater, e.g. childbirth

Question 7

describe the anatomical position and use correct anatomical terminology to describe body directions, regions, sections/planes, body cavities and associated membranes

Answer 7

anatomical position: body erect, face forward, feet together, palms face forward
supine: lying face upward
prone: lying face downward
directional terms:
- superior (cephalic) vs inferior (caudal)
- medial vs lateral relative to the midline
- proximal vs distal used to describe linear structures
- superficial vs deep relative to the surface of the body
- anterior (ventral) vs posterior (dorsal), anterior is forward and posterior is toward the back
body planes:
- median (through the midline) and sagittal (same plane, but to the left or right of median)
- frontal or coronal divides the body into anterior and posterior sections
transverse/cross divides body into superior and inferior sections
- oblique: other than at a right angle
planes of section through an organ:
- longitudinal: cut along the length of an organ
- cross/transverse: cut at right angle to length of the organ
- oblique: cut at any but a right angle
trunk cavities:
- diaphragm: divides the body cavity into thoracic and abdominopelvic cavities
- mediastinum: contains all structures of the thoracic cavity except the lungs
serous membrane:
- cover the organs of trunk cavities and line the cavity
- fist represents an organ
- inner balloon wall represents visceral serous membrane
- outer balloon wall represents parietal serous membrane
- cavity between two membranes filled with lubricating serous fluid that is produced by the membranes
- pericardium refers to the heart
- pleura refers to lungs and thoracic cavity
- peritoneum refers to abdominopelvic cavity

Question 8

define matter, mass, element and atom

Answer 8

matter: anything that occupies space and has mass
mass: the amount of matter in an object
element: the simplest type of matter with unique chemical properties; composed of atoms of only one kind
atom: smallest particle of an element that has chemical characteristics of that element

Question 9

describe atomic structure in terms of the three main subatomic particles and determine atomic number and mass number

Answer 9

atoms composed of subatomic particles
- neutrons no electrical charge
- protons one positive charge
electrons one negative charge
atomic number: equal to number of protons in each atom, which is equal to the number of electrons
mass number: number of protons plus number of neutrons

Question 10

define isotope, atomic mass, describe Avogadros number and define mole and molar mass

Answer 10

isotope: two or more forms of same element with same number of protons and electrons but different neutron number
atomic mass: average mass of naturally occurring isotopes
Avogadros number: displays number of units in one mole solution, 6.022 x 10^23
mole: Avogadros number of atoms, ions, molecules
molar mass: mass of one mole of a substance in grams, which is equal to its atomic mass units

Question 11

describe ionic and covalent bonding and hydrogen bonds

Answer 11

ionic bonding: atoms exchange electrons, are formed when a valence outer shell electron is transferred from one atom to another - much weaker
covalent bonding: two or more atoms share electron pairs, is stronger because the 2 atoms involved share 2 or more outer shell electrons
hydrogen bonds: occur when the positively charged H of one molecule is attracted to the negatively charged O, N or F of another molecule.

Question 12

distinguish between the different types of chemical reactions and the formulae used to describe them

Answer 12

synthetic reactions: two or more reactants chemically combine to form a new and larger product - anabolism
decomposition reactions: a large reactant is broken down to form smaller products - catabolism
reversible reactions: chemical reactions in which the reaction can proceed with from reactants to products or from products to reactants

Question 13

describe what enzymes are and how the body uses enzymes to regulate chemical reactions

Answer 13

enzymes (biological catalysts) proteinaceous catalysts that increase the rate of chemical reactions by lowering the activation energy necessary for reaction to begin
regulated through: temperature, concentration, catalysts

Question 14

define anabolism, catabolism and metabolism

Answer 14

anabolism: the constructive part of metabolism concerned especially with macromolecular synthesis
catabolism: molecules break down in the body for use as energy
metabolism: a chemical reaction that occurs in the body’s cells to change food to energy

Question 15

distinguish between a mixture and a solution

Answer 15

mixture: substances physically but not chemically combined (suspension - materials separate unless stirred, colloid - dispersal of tiny particles through a medium)
solution: mixture of liquids, gasses, or solids that are uniformly distributed and chemically combined (solvent: that which dissolved the solute, solute: that which dissolves the solvent)

Question 16

explain the different ways in which solution concentration can be expressed

Answer 16

percent: weight of a solute in a given volume of solvent
equivalents: a measure of the concentration of an ionised substance
molarity: number of moles of solute dissolved in 1 litre of solvent
osmolarity/osmolality: molarity x number of particles into which the solute dissociates

Question 17

briefly describe the role of electrolytes in the body

Answer 17

molecules or ions with an electrical charge
obtained by ingestion/diet
removed by kidneys, liver, skin, lungs
regulated by homeostatic mechanisms
help the body to regulate fluids and maintain the balance between fluids inside and outside cells

Question 18

describe what acids, bases and buffers are, and how pH effects the human body

Answer 18

acid: a proton donor or any substance that releases hydrogen ions
base: a proton acceptor or any substance that binds to or accepts hydrogen ions
buffer: a solution of a conjugate acid-base pair in which acid and base components occur in similar concentrations
pH can disrupt the body’s balance, which can lead to the development of bacteria, viruses, fungi, yeasts and parasites.

Question 19

describe the structure of proteins and nucleic acids and explain why they are important in the human body

Answer 19

proteins: composed of carbon, hydrogen, oxygen, nitrogen, sometimes iodine. functions: regulate processes, aid transport, protection, muscle contraction, structure, energy
nucleic acids: composed of carbon, hydrogen, oxygen, nitrogen, phosphorus
importance: carry the genetic blueprint of a cell and carry instructions for the functioning of the cell

Question 20

describe glycolysis

Answer 20

anaerobic respiration, breaking down glucose into 2 ATP molecules

Question 21

describe the major steps in lactic acid fermentation

Answer 21

where glucose is converted into cellular energy and the metabolic lactate

Question 22

describe the major steps in aerobic respiration

Answer 22

includes citric acid cycle and electron transport chain

creates 38 ATP molecules

Question 23

define glycogenesis, lipogenesis, glycogenolysis and gluconeogenesis

Answer 23

glycogenesis: excess glucose used to form glycogen
lipogenesis: when glycogen stores filled, glucose and amino acids used to synthesise lipids
glycogenolysis: breakdown of glycogen to glucose
gluconeogenesis: formation of glucose from amino acids and glycerol

Question 24

differentiate between the absorptive and post absorptive metabolic states

Answer 24

absorptive state: (storage) period immediately after eating when nutrients absorbed through intestinal wall into circulatory and lymphatic systems
postabsorptive state: (breakdown) occurs late morning, afternoon, night after absorptive state concluded, blood glucose levels maintained by conversion of other molecules to glucose

Question 25

define the term microbiology

Answer 25

is the study of microbes, either living organisms or non-living entities that cannot be seen with the naked eye

Question 26

discuss some of the applications of microbiology as well as the present and future challenges in medical microbiology

Answer 26

``` applications: - food production - bioremediation - use organisms to degrade environmental waste - synthesis of numerous products - genetic engineering - introduces genes of one organism into an unrelated organism to confer new properties on the organism future challenges: - infectious disease - COVID-19 pandemic - emerging diseases - resurgence of old diseases ```

Question 27

define the living organisms that exist in the microbial world

Answer 27

prokaryotes are unicellular, simple cells, dont have a nucleus eukaryotes are multicellular, contain organelles, have a membrane-bound nucleus

Question 28

name the three domains of all living organism and the properties that distinguish them from one another

Answer 28

three domains: organisms in each domain share certain disgusting properties - bacteria - archaea - eucarya

Question 29

describe the classification and structure of the algae, protozoa and fungi

Answer 29

algae: a diverse group of eukaryotic organisms, use light to convert carbon dioxide and water to carbohydrates, includes both microscopic unicellular and macroscopic multicellular organisms protozoa: microscopic unicellular organisms, lack photosynthetic capability, usually motile, usually transmitted by ingesting contaminated food or water, can be difficult to treat fungi: eukaryotes with a cell wall, yeast - unicellular, moulds - multicellular, cells organised into string, some fungi can exist as yeast or mould

Question 30

define taxonomy and describe how microorganisms are classified

Answer 30

is the science of naming, describing and classifying organisms identification: process of characterising in order to group them -microscopy, culture characteristics and other tests classification: arranging organisms into smaller or related groups nomenclature: system of assigning names

Question 31

describe the 3 types of infectious agents

Answer 31

vector: a living organism that transmits an infectious agent direct: spread when disease-causing microorganisms pass from the infected person to healthy person via direct physical contact indirect: spread when an infected person sneezes or coughs, sending infectious droplets in the air

Question 32

distinguish between viruses, viroid and prions and discuss the reasons why they are not organisms

Answer 32

viruses: non-living entities that can infect organisms of every domain. commonly referred to by organism they infect prions: are non-cellular infectious particles, appear to consist of miss-folded protein viroids: are infectious pieces of nucleic acid that infect plants not living entities

Question 33

what does the term 'normal flora' mean?

Answer 33

defined as populations of microorganisms routinely found growing on the body of healthy individual

Question 34

describe the types of relationships that exist between microorganisms and their hosts

Answer 34

mutualism: association in which both partners benefit commensalism: association in which one partner benefits and other is unharmed parasitism: association in which the microbe benefits at expense of the host

Question 35

explain the difference between resident flora and temporary flora

Answer 35

resident flora: typically inhabits body sites for extended periods temporary flora: transient, they form associations for a short time and are replaced

Question 36

describe the functions of normal flora and how they are influenced

Answer 36

protection against potentially harmful organisms - normal flora competitively excludes pathogens through covering binding sites used for pathogenic attachment, consume available nutrients, produce toxic compounds such as antibodies stimulate immune system: response mounted against normal flora that breaches bodys anatomical barriers, may cross-react with pathogen encountered later

Question 37

list the locations of the body where you would find high populations of normal flora

Answer 37

GI tract Genitourinary system respiratory system skin

Question 38

what are pathogens and opportunistic pathogens?

Answer 38

pathogens are organisms that can cause disease in otherwise healthy people opportunistic pathogens are microbes that cause disease when the bodys defences are down

Question 39

define virulence and infectious dose

Answer 39

virulence is a quantitative term referring to a pathogen disease-causing the ability infectious dose is the number of organisms required to establish infection

Question 40

describe the course of infectious disease

Answer 40

incubation: the time between the introduction of an organism to the onset of symptoms, the incubation period depends on numerous factors illness: follows incubation, individual experiences signs and symptoms of the disease convalescence: period of recuperation and recovery, infectious agents may still be spread

Question 41

what does the suffic -anemia mean

Answer 41

blood

Question 42

briefly describe the mechanisms of pathogenesis that microbes utilise

Answer 42

production of toxins that are ingested the colonisation of the surface of the host followed by toxin production invasion of host tissue invasion of host tissues followed by toxin production

Question 43

what are the 3 steps that are necessary for the establishment of infection?

Answer 43

adherence colonisation delivery of effector molecules to host cells

Question 44

how do microbes breach anatomical barriers?

Answer 44

penetration of skin | penetration of mucous membranes

Question 45

describe how microbes avoid host defences

Answer 45

hide within host - become out of reach of phagocytosis, avoid killing by complement proteins, avoid destruction by phagocytosis

Question 46

what is an exotoxin and what are the three types of exotoxin

Answer 46

most potent toxics known, are secreted by a bacterium or leak into surrounding fluids following cell lysis, made of protein - neurotoxins: cause damage to the nervous system, the major symptom is paralysis - entertoxins: damage to intestines and tissues of the digestive tract, major symptom is vomiting and diarrhea - cytotoxins - damage to a variety of cells, damage caused by interference with cell function or cell lysis

Question 47

how do viruses avoid the immune response

Answer 47

hide within cell, move from cell to cell

Question 48

what is selective toxicity

Answer 48

antibiotics cause greater harm to bacteria than human | doesnt kill everything, just bacteria

Question 49

explain the difference between bactericidal and bacteriostatic drugs

Answer 49

bacteriostatic are useful in situations when host defences cannot be relied upon to control pathogen bacteriocidal are useful in situations when host defences cannot be relied upon to control pathogen

Question 50

distinguish between narrow spectrum and broad spectrum drugs

Answer 50

narrow spectrum: work on a narrow range of organisms, gram-positive only or gram-negative only broad-spectrum: work on a broad range of organisms, gram-positive and gram-negative

Question 51

list the possible adverse effects of antimicrobial drugs

Answer 51

allergic reactions toxic effects suppression of normal flora antimicrobial resistance

Question 52

list the possible mechanisms of action of antimicrobial drugs

Answer 52

``` inhibition of cell wall synthesis inhibition of protein synthesis inhibition of nucleic acid synthesis inhibition of metabolic pathways interference with cell membrane integrity ```

Question 53

explain why the inhibition of cell wall synthesis is an effective mechanisms for an antibiotic

Answer 53

antimicrobials that interfere with the synthesis of cell walls do not interfere with eukaryotic cell, due to the lack of cell walls in animal cells in plant cells

Question 54

briefly discuss antimicrobial resistance

Answer 54

the microbes being targeted are no longer sensitive to the drug

Question 55

define communicable and non communicable disease?

Answer 55

communicable - disease transmitted from one host to another | non-communicable - diseases that do not spread from host to another

Question 56

define the following: morbidity, incidence, prevalence, endemic, epidemic, pandemic, outbreak

Answer 56

morbidity - the number of cases of illness in a given time period divided by population at risk incidence: reflects the number of new cases in a specific time period prevalence: reflects the total number of existing cases endemic: diseases that are constantly present epidemic: unusually large number of cases in a population pandemic - when epidemics spread worldwide outbreak - refers to a cluster of cases in a brief time affecting a specific population

Question 57

list the 3 reservoirs of disease

Answer 57

human non-human animal environmental

Question 58

what do the terms symptomatic/asymptomatic mean?

Answer 58

symptomatic - obvious source of infectious agents, ideally infected individuals understand the importance of precaustions asymptomatic - individual harbours pathogen with no ill effects

Question 59

what is a zoonoses and coliforms?

Answer 59

zoonoses - disease transmitted by non-human animal reservoirs coliforms - present in the environment and faeces, used to monitor H2O for faecal contamination

Question 60

describe the portals of entry and exit

Answer 60

portals of entry - pathogen must enter and colonize new host, route by which pathogen enters is the portal of entry, e.g. eyes portals of exit - microbes must leave one host in order to be transmitted to another

Question 61

what is the difference between horizontal/vertical transmission

Answer 61

horizontal transmission - transmission of the pathogen via contact with food, water or a living agent vertical transmission - transmission via transfer of the pathogen from mother to foetus or child through breast feeding

Question 62

discuss the different modes of contact with infectious agents or pathogens

Answer 62

direct contact transmission - occurs when one person physically touches another indirect contact transmission - involves transmission of pathogens by inanimate objects or fomites food and water (common vehicle transmission) - pathogens can be transmitted through contaminated food and water food and water - waterborne disease outbreaks can involve large numbers of people due to the fact that municipal water is distributed to large areas airborne (vehicle transmission) - respiratory droplets can be transmitted through the air vectors - any living organism that can carry a disease causing microbe

Question 63

describe the factors that influence the epidemiology of disease

Answer 63

dose - -minimum number of bacteria required to establish disease incubation period - disease with long incubation period can spread extensively before first case appears population characteristics - cerain population are more susceptible than others to certain pathogens

Question 64

describe population characteristics that influence occurrence of disease

Answer 64

immunity to pathogen - previous exposure or immunisation of population decreases susceptibility of population to organism general health - stresses such as malnutrition or overcrowing increases the susceptibility of population age - very young or very old to be at greater risk sex - influences disease distribution often due to anatomical differences religious and cultural practices - cultures that routinely breastfeed babies see less infectious disease in children genetic background - natural immunity can vary with genetic background

Question 65

how are diseases eradicated

Answer 65

improving sanitation reservoir and vector control vaccination antibiotic treatment

Question 66

what is nosocomial infection

Answer 66

hospital acquired infections (HAI), infections may range from mild to fatal

Question 67

list the common organisms that cause nosocomial infections

Answer 67

normal intestinal flora pneumonia and urinary tract and burn infections normal skin flora

Question 68

what are the reservoirs of infectious agents in hospitals

Answer 68

other patients hospital environment health care workers patients own normal flora

Question 69

how are nosocomial infections prevented

Answer 69

through development - infection control committee - infection control practitioner

Question 70

how can cross contamination be prevented

Answer 70

``` hand washing protective clothing universal precautions risk assessment waste management ```

Question 71

when should hands be washed and list the different types of handwashing

Answer 71

when to wash: - entering and leaving clinical areas - before contact with client - after contact with client - between procedures on same client - after going to toilet, blowing nose, touching own body or someone elses - after handling footwear types of handwashing: - household handwash - clinical handwash - procedures handwash - surgical scrub

Question 72

describe the use of soap in handwashing

Answer 72

surfactants in soap life soil and microorganisms from hands

Question 73

what are the universal precaustions

Answer 73

treat all patients as potentially infectious wear gloves whenever likely to contact with bodily fluids use protective barriers whenever splashing of body fluids is possible wash hands take steps to prevent sharps injuries

Question 74

what is clinical and infectious waste

Answer 74

clinical waste - material not contaminated with body fluids, paper hand towels, disposed of as garbage infectious waste - material contaminated with body fluids, faeces, yellow contaminated waster containers

Question 75

how are shaprs/needles/scalpels disposed

Answer 75

sharps - disposed in rigid-walled, speciallt labelled sharps containers needle - not to be re-sheathed, not be bent, do not remove syringe scalpel - do not remove scalple blade

Question 76

how are sharp injuries managed

Answer 76

``` dont panic encourage bleeding flush wound with disinfectant and copious amounts of water dress wound report to clinician complete sharps injury assessment form report to hospital for risk assessment take along sharp in sealed rigid-walled container ```

Question 77

how are blood spills managed

Answer 77

wear disposable gloves and plastic apron wear eyewear if risk of splashing mop up blood with disposable towels place all contaminated items in contaminated waste poor diluted sodium hypochlorite over area leave a few minutes and mop up place everything into contaminated waste container wash hands document incident

Question 78

what areas of the hospital have a requirement for very low numbers of microorganisms

Answer 78

``` operating theatres burns unit intensive care units transplant/oncology wards maternity wards paediatric wards ```

Question 79

define decontamination

Answer 79

the removal of possible harmful microorganisms from an object by cleaning or disinfecting

Question 80

define antiseptic

Answer 80

a type of chemical disinfectant, suitable for use on skin or living tissue, to kill or remove harmful microorganisms without damaging the tissue

Question 81

define disinfection

Answer 81

the destruction, removal or reduction in numbers of harmful microorganisms to an acceptable level

Question 82

define sterilisation

Answer 82

the complete destruction or removal of all microorganisms, including endospores

Question 83

define pasteurisation

Answer 83

a method of preserving milk and other liquids without altering their taste or quality. destroys bacteria responsible for spoilage and some pathogens, but not all microorganisms

Question 84

what is a germicide

Answer 84

any agent capable of killing microorganisms

Question 85

what is sanitation

Answer 85

thorough cleaning of an object or utensil to remove most microorganisms

Question 86

describe the structure of the plasma membrane

Answer 86

separation of intracellular and extracellular materials production of charge difference (membrane potential) across the membrane by regulation of intracellular and extracellular ion concentrations fluid mosaic model contain phospholipids, heads (hydrophilic) face outside and tails (hydrophobic) face inwards

Question 87

describe the functions of the lipids in plasma membrane

Answer 87

phospholipids - form a bilayer. polar heads facing water in the interior and exterior of the cell (hydrophilic); nonpolar tails facing each other on the interior of the membrane (hydrophobic) cholesterol - interspersed among phospholipids. amount determines fluid nature of the membrane fluid nature provides/allows - the distribution of molecules within the membrane, phospholipids automatically reassemble, if membrane is damaged, membranes can fuse with each other glycolipids - carbohydrate chains on the plasma membrane that allow cells to identify one anther or other molecules, used in: immunity, recognition of oocyte by sperm cell, intracellular communication

Question 88

describe the functions of the proteins in plasma membrane

Answer 88

membrane proteins - can be markers, attachment sites, channels, receptors, enzymes and carriers. intergral or intrinsic (extend deeply into membrane, often extending from one surface to the other. can form channels through the membrane), peripheral or extrinsic (attahced to intergral proteins at either the inner or outer surfaced of the lipid bilayer), function depends on 3D shape and chemical characteristics glycoprotiens - same as glycolipids channel proteins (integral) - a hydrophilic region faces inward and charge determines which molecules can pass through, non-gated ion channels are always open (responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest), gated ion channels can be open or closed (ligand gated ion channel: open when there is a change in charge across the plasma membrane, voltage-gated ion channel: open when there is a change in charge across the plasma membrane receptors - are proteins in membranes with an exposed binding site that can attach to specific molecules and act as an intracellular communication system enzymes - some act to catalyze reactions at outer/inner surface of plasma membrane carrier proteins - integral proteins move solutes from one side of membrane to the other, have specific binding sites, protein change shape to transport ions or molecules, are a type of transport protein

Question 89

cellular organelles and their functions

Answer 89

cytosol - fluid portion, dissolved molecules (ions in water) and colloid (proteins in water). cytoplasm - material outside the nucleus but inside the plasma membrane, composed of: cytosol, cytoskeleton, cytoplasmic inclusion, organelles cytoskeleton - supports the cell but has to allow for movements like changes in cell shape and movements of cilia, made from: microtubles, microfilaments, intermediate filaments cytoplasmic inclusion: aggregates of chemicals such as lipid droplets, melanin nucleus - membrane-bound organelle contains nucleoplasm, chromatin and a nucleolus, and is surrounded by the nuclear envelope, DNA located here centrioles and spindle fibres - centrioles are located in the centrosome a specialised zone near the nucelus, center of microtubule formation, before cell division, centrioles divide, move to ends of cell and organise spindle fibres ribosomes - sites of protein synthesis, composed of a large and small subunit, can be free or attached, are made of protein and rRNA endoplasmic reticulum - rough (has attached ribosomes, proteins produced and modified here), smooth (no attached ribosomes, manufacture lipids) golgi apparatus - modification, packaging, distribution of proteins and lipids for secretion or internal use, vesicles join and leave from opposite sides mitochondria - major site of ATP synthesis, membranes: cristae (infoldings of inner membrane) and matrix (substance located in space formed by inner membrane), increases in number when cell energy requirements increase, contains DNA that codes for some of the proteins needed for mitochondria production.

Question 90

describe the organisation of DNA into chromosomes

Answer 90

chromatin - dna complexed with proteins (histones), during cell division, chromatin condenses into pairs of chromatids called chromosomes. each pair of chromatids is joined but a centromere

Question 91

define interphase and describe the activites in cells life cycle

Answer 91

G1 phase, S phase, G2 phase, PMAT cytokinesis - division of cell cytoplasm mitosis - series of events that leads to the production of two cells by division of a mother cell into two daughter cells, cells are genetically identical, (prophase, metaphase, anaphase and telophase) interphase - phase between cell divison, replication of DNA, ongoing normal cell activities, growth and production of organelles

Question 92

define mitosis and list the events that occur during prophase, metaphase, anaphase, telophase and cytokenesis

Answer 92

mitosis - processof nucleur divison in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells prophase - chromosomes condense and centrosomes move to opposite sides of the nucleus, initiating formation of the mitotic spindle metaphase - chromosomes line up at the metaphase plate, under tension from miotic spindle anaphase - sister chromatids separate from each other and are pulled towards opposite ends of the cell telophase - chromosomes arrive at cell poles, the mitotic spindle disassembles and the vesicles that contain fragments of the original nucelus membrane assemble around the two sets of chromosomes cytokenesis - four stages (initiation, contraction, membrane insertion and completion)

Question 93

describe the process of DNA replication

Answer 93

opening of the double helix and separation of the DNA strands (two strands of the DNA double helix uncoil at a specific origin), the priming of the template strand, and the assembly of the new DNA segment

Question 94

describe the production of mRNA via transcription

Answer 94

a gene is copied; its DNA is used as a pattern for RNA synthesis, complementary nucleotide pairs bind to each other, the mRNA strand is synthesised one base pair at a time after transcription mRNA molecule must be trimmed

Question 95

describe translation and describe the role of mRNA, rRNA, tRNA in the production of a protein at a ribosome

Answer 95

synthesis of a protein at the ribosomes using mRNA, tRNA and rRNA mRNA - carry the coding sequences for protein synthesis rRNA - direct the catalytic steps of protein synthesis tRNA - helps decode a messenger RNA (mRNA) sequence into a protein, carry amino acids to the ribosome

Question 96

define triplets, codons, anticodons

Answer 96

triplets - a three-base codon of the genetic code codons - a sequence of 3 consecutive nucelotides that codes for a specific amino acid or signals the termination of gene translation anticodons - a trinucleotide sequence complementary to that of a corresponding codon in a messenger RNA sequence

Question 97

describe the genetic code

Answer 97

term used for the way the four bases of DNA are strung together in a way that the cellular machinery, the ribosome, can read them and turn them into a proteins

Question 98

define integral, peripheral and transport proteins in the plasma membrane

Answer 98

integral - extend deeply into membrane, often extending from one surface to the other, can from channels through the membrane peripheral - attached to integral proteins at either the inner or outer surfaces of the lipid bilayer transport - protein that serves the function of moving other materials with an organism

Question 99

define non-gated, ligand-gated and voltage-gated ion channels

Answer 99

non-gated - always open, responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest ligand-gated ion channel- open in response to small molecules that bind to proteins or glycoproteins voltage-gated ion channel - open when there is a change in charge across the plasma membrane

Question 100

describe how carrier proteins and ATP-powered pumps move ions and molecules across the membrane

Answer 100

molecule or solute binds to site, sometimes energy source is needed to move molecule to other side of membrane, incites the carrier to alter its shape resulting in the release of the bound molecule or solute

Question 101

define symport and antiport

Answer 101

symport - a mechanism of transport across a membrane in which two different molecules move in the same direction antiport - membrane protein that transports two molecules at the same time in the opposite direction

Question 102

explain how a chemical signal can bind to a receptor in the plasma membrane and cause a change in the activity of a cell

Answer 102

when a signalling molecule joins with an appropriate receptor on a cell surface, this binding triggers a chain of events that not only carriers the signal to the cell interior, but amplifies it as well

Question 103

define diffusion, osmosis and osmotic pressure

Answer 103

diffusion - movement of solutes from an area of high concentration to lower concentration in solution osmosis - diffusion of water (solvent) across a selectively permeable membrane osmotic pressure - force required to prevent water from moving across a membrane by osmosis

Question 104

define filtration

Answer 104

works like a sieve depends on pressure difference on either side of a partition moves from side greater pressure to lower

Question 105

define mediated transport

Answer 105

involve carrier proteins or channels in the cell membrane | move larger, water soluble molecules or electrically charged molecules across the plasma membrane

Question 106

define endocytosis, receptor-mediated endocytosis, phagocytosis and pinocytosis

Answer 106

endocytosis - internalization of substances by formation of a vesicle, types: phagocytosis, pinocytosis, receptor-mediated endocytosis receptor-mediated endocytosis - cells absorb metabolites, hormones, proteins and viruses by the inward budding of the plasma membrane phagocytosis - ingest solid particles into the cell pinocytosis - cell takes in the fluids along with dissolved small molecules

Question 107

describe exocytosus

Answer 107

accumulated vesicles containing products or waste are expelled from cell

Question 108

describe receptor/ligand-mediated communication, specificity, up-regulation and down-regulation

Answer 108

portion of molecule where ligand binds is called binding site if the molecule is a receptor the binding site is called a receptor site ligand/receptor site is specific the purpose of binding to target tissue is to elicit a response by the target cell down-regulation - causes the number of receptors to decrease, can occur after cells are exposed to a ligand up-regulation - increase in synthesis of receptors for a hormone, thus increases sensitivity to that hormone

Question 109

explain mechanisms involved in receptor-mediated communication

Answer 109

membrane bound receptors - integral proteins with receptor site at extracellular surface, interact with ligands that cannot pass through the plasma membrane intracellular receptors - receptors in the cytoplasm or in the nucleus