IB HL BIO YR 2 UNIT THREE-B

enveloped viruses

impact animals

become covered in a membrane when leaving their host

phospholipids come from the host and proteins come from the virus

non-enveloped viruses

impact plants and bacteria

are not closed in a membrane

bacteriophage lambda

in the bacteriophage family

non-enveloped

double stranded DNA

host = e-coli

COVID-19

coronaviridae family

enveloped

linear single stranded RNA

host = birds, humans

HIV

retriviridae family

enveloped

linear single stranded RNA

host = humans

uses reverse transcriptase to convert RNA to DNA without proofreading → high mutations

host cells convert the virus’s RNA’s cytosine into uracil → more mutations

lytic cycle

phage attaches to host, injects its DNA, replicates DNA and makes proteins, breaks out of host cell to infect other cells

very fast acting

lysogenic cycle

temperate

causes minimal harm

can break out and go into lytic cycle

phage enters cell, phage DNA becomes incorporated into host DNA, host replicates, under stressful conditions, phase DNA is excised and enters lytic cycle

regressive hypothesis (virus origins)

viruses are remnants of cells that lost components and became self reliant

reductive evolution

loss of translation

obligate parasitism

progressive hypothesis (virus origins)

viruses were built by modifying cell components

influenza

8 negative single stranded RNA with RNA replicase that does not proofread during replication → high mutation rate

2 proteins in the membrane can exchange and create new combinations to make a novel virus

pathogen

disease-causing organism

typically describes an infectious agent (virus, bacterium, protazoa, fungus, etc)

transmitting by body fluids, contaminated food, direct contact, etc

bacteria

no nucleus, cell wall (peptidoglycan), prokaryotic, reproduces through binary fission

treated with anti-biotics

ex- e-coli

fungus

eukaryotic, unicellular, cell wall (chitin)

invade host tissue

ex- athlete’s foot

skin

body’s first line of defense

physical barrier to separate outside and inside

has sebaceous glands to keep moist & low pH

mucous membranes

found in vagina, foreskin, airways leading to lungs, etc

contain lysosomes and cilia that push mucus to be swallowed → stomach acids kill any pathogens

clotting factors

proteins in blood that control bleeding

released by platelets

blood clotting cascade of events

1. platelets gather at site of injury and release activator

2. prothrombin activator, vitamin K, and calcium ions cause prothrombin to turn into thrombin (active enzyme)

3. thrombin converts fibrinogen (soluble) to fibrin (insoluble) at the site of the injury

4. red blood cells get stuck in fibrin fibers

5. _____ ____ is formed

pacemaker (sinoatrial node)

initiates and controls the rate of the heartbeat

atrioventricular (AV) valves

prevent backflow of blood from ventricles to atria

semilunar valves

prevent backflow of blood from arteries to ventricles

arteries

take blood away from the heart

all oxygenated blood (except pulmonary artery)

thicker wall, narrow lumen, more structure

veins

take blood to the heart

all deoxygenated blood (except pulmonary vein)

lower pressure

thinner wall, wider lumen, less structure

atria

receive blood from body and lungs

ventricles

pump blood back into body and lungs

cardiac muscle

allows the heart to contract in order to create high pressure

myogenic

artery adaptations to withstand/maintain high blood pressure

smooth muscle to maintain blood pressure between heart beats

collagen in outer wall, thick wall to strengthen

elastic fibers in wall to stretch and recoil and pressure increases and decreases, helps keep blood moving

narrow lumen

vein adaptations for the return of blood to the heart

valves prevent backflow of blood

thin wall, compressed by skeletal muscles to move blood

wide lumen, large blood volume

capillaries

exchange materials (oxygen, co2, nutrients) between veins and arteries

highly branched with narrow diameters

one cell thick, rapid diffusion

atherosclerosis

hardening and narrowing of arteries because of build up of cholesterol/triglycerides/etc substances on artery walls

no cure yet but diet can help slow it down

occlusion of coronary arteries

atherosclerosis in coronary arteries

can cause death of heart tissue and heart attack

coronary arteires

supply the heart with oxygen and nutrients

tissue fluid

composed of dissolved nutrients, dissolved oxygen, metabolic wastes, white blood cells

contain a high concentration of nutrients and oxygen and a low concentration of waste (opposite of cells in order to create a concentration gradient where oxygen diffuses into cells and waste diffuses out of cells)

Hemoglobin

protein found in RBCs of vertebrates

responsible for transporting oxygen from the lungs to respiring tissues and transporting co2 from respiring tissues back to lungs

Fetal hemoglobin (HbF)

type of hemoglobin produced by developing fetus

remains in infant until about 6 months of age

higher affinity for oxygen than adult hemoglobin because of its gamma polypeptides (instead of beta)→ increases efficiency with which the fetus can obtain oxygen

important because o2 concentration in fetus is lower than that of mom

Adult hemoglobin (HbA)

type of hemoglobin produced once a baby is born and throughout life,

lower affinity for oxygen than HbF because it has a higher affinity for an organic phosphate that's found in RBCs and also the presence of beta polypeptides (instead of gamma)

Cooperative binding

once one oxygen molecule binds to hemoglobin, it's easier for other oxygen molecules to do the same

reverse is also true (once one detaches, the affinity decreases and others detach too)

Allosteric binding

co2 binds to allosteric region of hemoglobin to be taken to lungs for exhalation

when co2 binds, decreases affinity for oxygen

Diffusion

the movement of molecules from a region of higher concentration to a region of lower concentration, does not require energy

Trachea/Windpipe

passageway, takes air from nose/mouth to lungs, covered in cilia to trap dust/pathogens, has cartilage to protect it

Bronchus

tube connecting trachea to lungs

Bronchioles

smaller passageways for air, connect bronchi and alveoli

Alveolus / Alveoli

thin air sacs, terminal parts of lungs, surrounded by a dense network of capillaries, where gas exchange occurs, increase surface area in lungs

Gills

specialized respiratory organ found in many aquatic animals, allows extraction of dissolved o2 from h2o and expel co2, responsible for gas exchange

Surfactant

a complex mixture of lipids and proteins that lines the surface of the alveoli, decrease surface tension and aids diffusion, produces a monolayer of phospholipids during expiration that prevents watery surfaces from sticking to the inside of the alveoli

Ventilation

the flow of air into and out of the alveoli

Inspiration

air entering the lungs, eg breathing in, increases concentration gradient of o2 between alveoli and blood so o2 diffuses into blood

Expiration

air exiting the lungs, eg breathing out, increases concentration gradient of co2 between alveoli and blood so co2 diffuses out of blood

Diaphragm

dome shaped muscle, separates thorax and abdomen, needed for ventilation, during inspiration- relaxes, during expiration- contracts

Thorax

The area of the body between the neck and the abdomen, contains vital organs (heart, lungs, etc)

External Intercostal Muscles

outermost set of muscles located between ribs, contract to move ribs up during inspiration, relax to move ribs down during expiration

Internal Intercostal Muscles

innermost set of muscles between ribs, relax during inhalation to allow air to move into lungs, contract during expiration to push air out of lungs

Abdominal Muscle

help to maintain consistent internal pressure, contract to push diaphragm up and expel air from lungs

Tidal Volume

normal volume of air breathed in/out during a normal/resting breath

Inspiratory Reserve

forcefully inhaled air after a normal tidal volume inhalation

Expiratory Reserve

forcefully exhaled air after a normal tidal volume exhalation

Vital Capacity

total volume of air that can be exhaled after a maximal effort inhalation and vice versa

Spirometer

measures lung/tidal volume and lung/vital capacity as a function of time

Oxygen Dissociation Curve

graph that shows the percent of o2 saturation of hemoglobin against the concentration of available o2 (partial pressure, kPa), sigmoid shaped curve because of cooperative binding

Oxygen Affinity

the strength of the bond between hemoglobin and oxygen, higher when more oxygen is bound to the hemoglobin molecule

Partial Pressure (of o2)

pressure of o2 in a mixture of gases (air), 20.9 kPa

Haem Group

the non-protein group of iron atoms on a hemoglobin molecule, the part that o2 binds to

Bohr Shift

a decrease in pH (because of co2) shifts the o2 dissociation curve to the right

Carbonic Anhydrase

speeds up the reaction between CO2 and water, prevents drastic changes in pH

Lumen

space inside a tube that substances can pass through, smaller → higher pressure, veins have wider ones than arteries

Coronary Heart Disease

disease in which there is a narrowing or blockage of the coronary arteries, usually caused by atherosclerosis

Blood Plasma

fluid part of the blood that carries the blood cells, forms blood clots

Hydrostatic Pressure

the pressure exerted by a fluid confined within a space, driving force for fluid movement between capillaries and tissues, pushes blood out of capillaries and into the interstitial space to form tissue fluid

Oncotic Pressure

the pressure exerted by plasma proteins, draws fluid back into capillaries, opposite of hydrostatic pressure, most of tissue fluid returns to blood because of this

Single Circulation

blood flows through the heart only once per circuit, seen in fish

Double Circulation

blood passes through the heart twice, once for oxygenation (heart → lungs → heart) and once for systemic circulation (heart → body tissues → heart), seen in mammals and birds

Systole

contraction of heart muscles

Diastole

relaxation of heart muscles

Myogenic

type of muscle, contract without any external stimulus, ex- heart muscle

Atrioventricular Node

initiates an action potential which rapidly spreads across atria and causes an atrial systole/contraction

Bundle of His

located in the septum between the ventricles, receives electrical impulses from the AV node and transmits them to the ventricles (but there is a pause so that all four chambers don't contract at once)

Purkinje Fibres

located in the inner ventricular walls, play a crucial role in transmitting electrical impulses from the bundle of his to the ventricles, enable coordinated and synchronized heart contractions

Virus

an infectious microbe consisting of a segment of nucleic acid (DNA or RNA) surrounded by a protein coat, not living, fixed size, can be enveloped or non enveloped

Lysogen

a bacterial cell that has been infected and is in the lysogenic cycle, can produce and transfer the ability to produce a phage

Antibodies

a protein produced by the immune system in response to the presence of an antigen

Antigens

any substance that triggers an immune response, causes body to produce antibodies to fight it

Antigenic drift

the gradual, small changes or mutations in the genes of viruses that lead to alterations in their surface proteins, allow virus to possible evade host’s immunity

Antigenic shift

a major/abrupt change in the antigens of a virus, leads to emergence of a new, distinct viral subtype that will evade immunity

Lysosome

a membrane-bound cell organelle that contains digestive enzymes, destroy pathogens

Phagocyte

engulfs around anything foreign, non specific, can become an antigen presenting cell

Memory Cells

hold memory of antigen for the next infection to make antibodies quicker

Antigen presenting cell (APC)

cell that captures, processes/destroys, and presents antigens on its surface

Clonal Selection

when b cells are activated, they make antibodies and memory cells

B Lymphocytes/B-cells

makes antibodies, have a large number of RER → make ribosomes → proteins/antibodies for export, can bind to antigen directly and then present the antigen

Synapses

tiny gap at junction between two nerve cells or a neuron or an effector (muscle/gland), signals must cross here, neurotransmitters can only go pre to post synapse, energy goes from electrical to chemical back to electrical

Fibrinogen

a soluble plasma protein, converted into fibrin using thrombin

Fibrin

a fibrous, insoluble protein that forms the primary structure of blood clots, made when thrombin converts fibrinogen into it, RBCs get stuck in the fibers and a blood clot forms

Innate Immune System

immunity that were born with, includes first and second lines of defence, non specific (response is same for all pathogens)

Adaptive Immune System

immunity that we gain after being exposed to a pathogen, two types- humoral and adaptive

Humoral Immunity

b-cells, bind with pathogens and become APCs, secrete antibodies that defend against pathogens

Cell Mediated Immunity

t-cells, bind with an APC, defendants against infected cells in our body

Lysosome

breaks down pathogens after phagocytosis

Phagosome

a membrane-bound vesicle formed within a phagocyte that engulfs a pathogen through phagocytosis

Lymphocytes

a type of white blood cell that play a crucial role in the adaptive immune system, two types - b-helper and t-helper

T4 Helper Lymphocytes/Helper T Cells

disperses chemical signals to activate other immune cells, binds to the pathogen that is presented on the surface of the phagocyte (if the pathogen presented matches up with the site), do not interact with free pathogens, part of the cell mediated immune response

Memory Cells

hold memory of antigen for the next infection to make antibodies quicker