bio Flashcards
explain the formation of hydrogen between water and other polar molecules
hydrogen bonds form between hydrogen and a strongly electronegative element such as oxygen. in water hydrogen bonding helps to hold the water molecules together making it a stable substance
why does methane have a lower boiling point than water
because methane does not have any hydrogen bonds, weakly held together.
use an example: how are hydrophobic/philic molecules transported in blood
Hydrophilic molecules, which are attracted to water, require transport proteins to help them cross the cell membrane. Hydrophobic molecules, which repel water, can directly diffuse through the membrane via passive transport. Both types of molecules rely on the membrane’s selective permeability.
why is amylopectin, even though similar to glycogen, less soluble?
more 1-6 glycosidic bonds in glycogen, more branching, more surface area to interact between molecules of water and glycogen, more solubility
what makes the amino acids in proteins unique
r group
define primary secondary tertiary quaternary structure
primary - sequence of amino acids in polypeptide chain
secondary - formation of α-helices and β-pleated sheets stabilised by hydrogen bonding. The secondary structure is the way a polypeptide folds in a repeating arrangement to form α-helices and β-pleated sheets
tertiary - tertiary structure is the further folding of the polypeptide stabilised by interactions between R groups
The tertiary structure is the way the polypeptide chain coils and turns to form a complex molecular shape (i.e. the 3D shape)
It is caused by interactions between R groups; including H-bonds, disulfide bridges, ionic bonds and hydrophobic interactions
quaternery - the quaternary structure exists in proteins with more than one polypeptide chain
Which layer of the veins and arteries contains the muscle and elastic fibres?
Tunica media
Which type of cell secretes mucus into the lumen of the small intestine to facilitate the movement of the chyme?
Goblet cell
State the name of the molecule that CDKs attach to proteins in order to activate them.
phosphate group
define detritivore
Detritivores are a type of heterotroph, or organisms that consume dead and decaying organic matter known as detritus to obtain energy and nutrition.
define saprotroph
Saprotrophs are heterotrophs that obtain their organic nutrients from dead organisms by external digestion.
Saprotrophs are heterotrophs that ingest the tissues of dead organisms and waste material by secreting enzymes onto their food and digesting it externally before absorbing the products of this digestion. .
define autotroph
Autotrophs make use of abiotic factors to produce their own food.
what is nutrient cycling
The nutrient cycle is a system where energy and matter are transferred between living organisms and non-living parts of the environment. This occurs as animals and plants consume nutrients found in the soil, and these nutrients are then released back into the environment via death and decomposition.
whats reproductive isolation
Reproductive isolation of populations can be temporal, behavioural or geographic. Reproductive isolation occurs when barriers prevent two populations from interbreeding – keeping their gene pools separate.
what are abiotic factors
An abiotic factor is a non-living part of an ecosystem that shapes its environment. In a terrestrial ecosystem, examples might include temperature, light, and water.
what is speciation
formation of a new species from an original, ancestral lineage
how can reproductive isolation lead to speciation
reproductive isolation is when two or more populations of the same species are prevented from interbreeding. if the populations never interbreed then gene mixing between the populations stops and evolutionary forces such as natural selection may act differently on the populations. over time the populations may change to the point of not being able to interbreed and produce viable fertile offspring in which the case they would now be considered seperate species
how does the ocean become more acidic
Typically, when carbon dioxide is dissolved in the ocean, it combines with water molecules to form carbonic acid (H2CO3)
The carbonic acid then dissociates to form bicarbonate ions (HCO3–) and hydrogen ions (H+)
The ocean also contains carbonate ions (CO3–), which are absorbed by coral and molluscs to form calcium carbonate (CaCO3)
Calcium carbonate is used to form the hard exoskeletons of reef-building corals and is used by molluscs to develop shells
H+ ions can reduce the stock of carbonate ions in the ocean by combining with it to form bicarbonate
Hence, the levels of H+ ions must be kept low to ensure that their is sufficient stock of carbonate ions for aquatic organisms
As a result of deforestation and the increased burning of fossil fuels, atmospheric carbon dioxide concentrations have increased
With more CO2 being absorbed by the oceans, there is an associated increase in the production of H+ ions
These H+ ions lower the pH of the ocean, causing acidification (ocean pH has dropped ~0.2 since the industrial revolution)
The H+ ions will also combine with carbonate ions, reducing the amounts available to marine organisms
This will result in the formation of thinner, deformed shells and reduce the population numbers of reef-building corals
The reduction in pH will also dissolve calcium carbonate structures, enhancing the damage to shells and corals
Autotrophs absorb both dissolved carbon dioxide and hydrogen carbonate ions and use them to produce organic compounds
how is calcium carbornate and limestone created
When the hydrogen carbonate ions come into contact with the rocks and sediments on the ocean floor, they acquire metal ions
This commonly results in the formation of calcium carbonate and the subsequent development of limestone
Living animals may also combine the hydrogen carbonate ions with calcium to form calcium carbonate
This calcium carbonate forms the hardened exoskeleton of coral, as well as forming the main component of mollusca shells
When the organism dies and settles to the sea floor, these hard components may become fossilised in the limestone
how is methane produced
Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground
what are methanogens
Methanogens are archaean microorganisms that produce methane (CH4) as a metabolic by-product in anaerobic conditions
what are anaerobic conditions
Wetlands (e.g. swamps and marshes)
Marine sediments (e.g. in the mud of lake beds)
Digestive tract of ruminant animals (e.g. cows, sheep, goats
why is the methane level in atmosphere not very large even though it has significant quantity
The lifetime of methane gas once it reaches the atmosphere is around 10-12 years · This is because methane is oxidised in the atmosphere.
what determines the impact of a gas in the atmosphere
The impact of a gas depends on its ability to absorb long-wave radiation as well as its concentration within the atmosphere
- Ability to absorb long-wave radiation
Gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact (per molecule)
- Concentration within the atmosphere
The greater the concentration of a gas, the greater its warming impact will be within the atmosphere
The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere
The overall impact of a greenhouse gas will be determined by the combination of both these factors
Methane has a larger capacity to absorb long-wave radiation than carbon dioxide, but is significantly less abundant
Water vapour enters the atmosphere rapidly but only remains for short periods, while carbon dioxide persists for years
Human activity is increasing the amount of greenhouse gases (except water vapour) and hence increasing their impact
what are the consequences of ocean acidification
An increase in ocean acidification as a result of elevated anthropomorphic CO2 emissions could have several consequences:
The disappearance of coral reefs could result in a loss of shoreline protection and habitat, altering coastal ecosystems
The loss in revenue from tourism and food industries is predicted to cost economies upwards of $1 trillion by 2100
Increasing the dissolved CO2 levels in oceans would cause invasive species of algae to flourish (more photosynthesis)
define heterozygous
each of the homologous chromosomes contain a different allele for the gene
whats a homologous chromosomes pair
each chromosome of a homologous pair comes from a different parent
they contain the same sequence of genes for the same trait, but the versions of the genes (alleles) on each chromosomes may differ
whats the significance of genes existing as alleles
alleles are different forms of a gene coding for the same trait. different alleles provide phenotypic variation for the expression of a gene.
define mutation
gene mutation is a change in the nucleotide sequence of a section of DNA coding for a specific trait. New alleles are formed by mutation.
what chemicals can cause mutagens
benzene
what is a mutagen
A mutagen is a chemical or physical agent capable of inducing changes in DNA called mutations.
what type of mutation/disease is sickle cell anemia
sickle cell anemia is a autosomal recessive disease caused by a point mutatin
why is sickle cell anemia more prevelent in places with high malaria
he malaria parasite, Plasmodium, struggles to survive in sickled red blood cells, which tend to sickle under low oxygen conditions, making them less hospitable for the parasite. Additionally, sickled cells are more likely to be removed by the spleen, reducing infection rates. This protective effect has contributed to the persistence of the sickle cell trait in malaria-endemic regions, demonstrating an example of natural selection.
whats ice age
Inherited variation exists within the population
Competition results from an overproduction of offspring
Environmental pressures lead to differential reproduction
Adaptations which benefit survival are selected for
Genotype frequency changes across generations
Evolution occurs within the population
what are 3 ways of genetic variation
Mutations – Changing the genetic composition of gametes (germline mutation) leads to changed characteristics in offspring
Meiosis – Via either crossing over (prophase I) or independent assortment (metaphase I)
Sexual reproduction – The combination of genetic material from two distinct sources creates new gene combinations in offspring
the binomial name system what comes first
genus in caps then species
name and identify the 3 domains of life
Eukarya – eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)
Archaea – prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)
Eubacteria – prokaryotic cells lacking a nucleus and consist of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)
whats the pneumonic for taxonomy
katie perry comes over for grape soda
wings in birds and bats. analogous or homologous
analogous
explain the figwort situation, why was it reclassified
Until recently, figworts were the 8th largest family of flowering plants (angiosperms), containing 275 different genera
This was problematic as many of the figwort plants were too dissimilar in structure to function as a meaningful grouping
Taxonomists examined the chloroplast gene in figworts and decided to split the figwort species into five different clades
Now less than half of the species remain in the figwort family – which is now the 36th largest among angiosperms
difference between introns and extrons
introns are non coding part /region of dna
extrons are protein coding regions of dna
define chromatin, chromatid, chromosome
Chromosomes: Chromosomes are long, coiled structures made of DNA and proteins that carry genetic information and are found in the nucleus of cells.
Chromatin: Chromatin is the less condensed form of DNA and proteins found in non-dividing cells, which allows for gene expression and DNA replication.
Chromatids: Chromatids are the two identical halves of a duplicated chromosome that are joined together at the centromere and separated during cell division.
whats the word starting with t that was observed through the davson danielli model
trilaminar
where does the pancreas secrete enzymes into
lumen
what is secreted by the pancreas
amylase, lipase, endopeptidase
what remains undigested
cellulose
food travels down oesophagus as a b__
bolus
whats the movement of contraction for digestion
Continuous segments of longitudinal smooth muscle rhythmically contract and relax (perstalsis)
what is segmentation
Segmentation involves the contraction and relaxation of non-adjacent segments of circular smooth muscle in the intestines
Segmentation contractions move chyme in both directions, allowing for a greater mixing of food with digestive juices
While segmentation helps to physically digest food particles, its bidirectional propulsion of chyme can slow overall movement
features of villi
Microvilli – Ruffling of epithelial membrane further increases surface area
Rich blood supply – Dense capillary network rapidly transports absorbed products
Single layer epithelium – Minimises diffusion distance between lumen and blood
Lacteals – Absorbs lipids from the intestine into the lymphatic system
Intestinal glands – Exocrine pits (crypts of Lieberkuhn) release digestive juices
Membrane proteins – Facilitates transport of digested materials into epithelial cells
whats something that dialysis tubing is not but membranes are
Unlike the membranes of living cells, dialysis tubing is not selectively permeable based on charge (ions can freely cross)
what did william harvey deduce/propose
arteries and veins part of a singular network
heart acts like pump
two circulation loops
double circulation
whats atherosclerosis
plaque buildup via fatty deposits
define pathogen
disease causing agent
structure of aveleous
They have a very thin epithelial layer (one cell thick) to minimise diffusion distances for respiratory gases
They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood
They are roughly spherical in shape, in order to maximise the available surface area for gas exchange
Their internal surface is covered with a layer of fluid, as dissolved gases are better able to diffuse into the bloodstream
what does surfactant do
reduce surface tension
causes and consequences of emphysema
Emphysema is a lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls
The loss of elasticity results in the abnormal enlargement of the alveoli, leading to a lower total surface area for gas exchange
The degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae)
The major cause of emphysema is smoking, as the chemical irritants in cigarette smoke damage the alveolar walls
The damage to lung tissue leads to the recruitment of phagocytes to the region, which produce an enzyme called elastase
This elastase, released as part of an inflammatory response, breaks down the elastic fibres in the alveolar wall
Elastase activity can be blocked by an enzyme inhibitor (α-1-antitrypsin), but not when elastase concentrations are increased
A small proportion of emphysema cases are due to a hereditary deficiency in this enzyme inhibitor due to a gene mutation
Common symptoms of emphysema include shortness of breath, phlegm production, expansion of the ribcage, cyanosis and an increased susceptibility to chest infections
main purpose of myelin sheath
he main purpose of the myelin sheath is to increase the speed of electrical transmissions via saltatory conduction
In myelinated neurons, the action potentials ‘hop’ between the gaps in the myelin sheath called the nodes of Ranvier
This results in an increase in the speed of electrical conduction by a factor of up to 100-fold
where is melatonin produced
pineal gland
purpose of melatonin
control circadian rythyms
what causes the y chromosome
The SRY gene codes for a testis-determining factor (TDF) that causes embryonic gonads to form into testes (male gonads)
In the absence of the TDF protein (i.e. no Y chromosome), the embryonic gonads will develop into ovaries (female gonads)
where is fsh secreted from
anterior pituitary
describe the menstrual cycle
- Follicular Phase
Follicle stimulating hormone (FSH) is secreted from the anterior pituitary and stimulates growth of ovarian follicles
The dominant follicle produces estrogen, which inhibits FSH secretion (negative feedback) to prevent other follicles growing
Estrogen acts on the uterus to stimulate the thickening of the endometrial layer
- Ovulation
Midway through the cycle (~ day 12), estrogen stimulates the anterior pituitary to secrete hormones (positive feedback)
This positive feedback results in a large surge of luteinizing hormone (LH) and a lesser surge of FSH
LH causes the dominant follicle to rupture and release an egg (secondary oocyte) – this is called ovulation
- Luteal Phase
The ruptured follicle develops into a slowly degenerating corpus luteum
The corpus luteum secretes high levels of progesterone, as well as lower levels of oestrogen
Estrogen and progesterone act on the uterus to thicken the endometrial lining (in preparation for pregnancy)
Estrogen and progesterone also inhibit secretion of FSH and LH, preventing any follicles from developing
- Menstruation
If fertilisation occurs, the developing embryo will implant in the endometrium and release hormones to sustain the corpus luteum
If fertilisation doesn’t occur, the corpus luteum eventually degenerates (forming a corpus albicans after ~ 2 weeks)
When the corpus luteum degenerates, estrogen and progesteron levels drop and the endometrium can no longer be maintained
The endometrial layer is sloughed away and eliminated from the body as menstrual blood (i.e. a woman’s period)
As estrogen and progesterone levels are too now low to inhibit the anterior pituitary, the cycle can now begin again
explain ivf
In the IVF process, down regulation involves using drugs to halt the secretion of FSH and LH, which subsequently stops the release of estrogen and progesterone, allowing doctors to control the timing and quantity of egg production in the ovaries; this treatment typically lasts about two weeks and is administered as a nasal spray. Following this, superovulation is induced by injecting large doses of FSH to stimulate the development of multiple follicles, which are then treated with human chorionic gonadotrophin (hCG) to mature the eggs before they are collected through aspiration. The extracted eggs are incubated with sperm to facilitate fertilization, and success is confirmed by microscopic analysis. About two weeks before implantation, progesterone treatments are started to prepare the endometrium. Healthy embryos are then selected and transferred into the uterus (or that of a surrogate), with multiple embryos often transferred to increase the chances of successful implantation, leading to pregnancy testing two weeks later to check for success.
what is a stroke
sudden death of brain cells in a localised area due to inadequate blood flow
what part of neural tube expands to form brain
anterior
whats neuralation
neurulation refers to the folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube. The embryo at this stage is termed the neurula
what is a synapse
a junction at which a neuron transmits a signal to another cell
how come strokes can be temporary
Strokes symptoms may be temporary if the brain is able to reorganise its neural architecture to restore function
Following a stroke, healthy areas of the brain may adopt the functionality of damaged regions
This capacity for the restoration of normal function is made possible due to the neuroplasticity of the brain
name 2 strokes and function
Ischemic strokes result from a clot within the blood restricting oxygenation to an associated region of the brain
Hemorrhagic strokes result from a ruptured blood vessel causing bleeding within a section of the brain
what part of brain controls autonomic activities
medulla
sympathetic vs parasympathetic response
Sympathetic nerves release noradrenaline (adrenergic) to mobilise body systems (‘fight or flight’ responses)
Parasympathetic nerves release acetylcholine (cholinergic) to relax body systems and conserve energy (‘rest and digest’)
whats red green colour blindness
genetic disorder whereby an individual fails to discriminate between red and green hues
whats the word that amount of brain mass relative to an animal’s body mass
encephaliazation
how much of body energy does brain consume
20%
whats vestibular system
sensory system in the inner ear that is involved in balance and spatial orientation (proprioception)
describe olfaction
Olfaction is the ability to detect airborne chemicals (odorants) as scents or smells
At the back of the nasal cavity is a patch of tissue called the olfactory epithelium, which is embedded with chemoreceptors
The olfactory epithelium is lined with mucus, in which odorant molecules will dissolve before binding to the chemoreceptors
Binding of an odorant molecule will trigger a nerve impulse, which is transferred via the olfactory bulb to the brain
The combination of olfactory receptors activated determines the specific scent perceived by the brain
why are standard hearing aids ineffective in deaf patients
they amplify sounds but do not bypass defective hearing structures
cochear implants contain 2 parts. they are….
external part (microphone, trnansmitter)
internal part (reciever/stimulator)
describe how cochlea implants work
The external components detect sounds, filter out extraneous frequencies and then transmit the signals to the internal parts
The internal components receive the transmissions and produce electrical signals via electrodes embedded in the cochlea
The electrical signals are then transferred via the auditory nerve to be processed by the brain
- Basic Function
Cochlear implants are medical devices that bypass damaged parts of the ear and directly stimulate the auditory nerve to provide a sense of sound to individuals with severe hearing loss. They are designed for people whose hearing loss is caused by damage to the hair cells in the cochlea, which normally detect sound vibrations and convert them into electrical signals sent to the brain. - Components of a Cochlear Implant
A cochlear implant consists of two main parts:
External components:
Microphone: Captures sound from the environment.
Speech processor: Selects and arranges sounds captured by the microphone.
Transmitter: Sends the processed signals to the internal implant via radio waves.
Internal components:
Receiver: Implanted under the skin, it converts the radio signals into electrical impulses.
Electrode array: A series of electrodes surgically implanted into the cochlea. These electrodes directly stimulate the auditory nerve by sending electrical signals that represent sound.
3. Mechanism of Action
Sound Detection: The microphone in the external part picks up sounds from the environment.
Sound Processing: The sound processor converts these sounds into digital signals. These signals are processed to emphasize certain frequencies, particularly speech sounds.
Transmission: The transmitter sends these signals to the internal receiver through a magnetic connection across the skin.
Electrical Stimulation: The internal receiver converts the digital signals into electrical impulses, which are sent to the electrode array inside the cochlea.
Nerve Stimulation: The electrodes stimulate different parts of the auditory nerve depending on the frequency of the sound. Low-frequency sounds stimulate deeper areas of the cochlea, while high-frequency sounds stimulate regions closer to the entrance.
Perception of Sound: The auditory nerve sends these electrical impulses to the brain, where they are interpreted as sound.
4. Limitations
Cochlear implants do not restore normal hearing but provide a useful representation of sounds.
They are most effective for individuals who have lost hearing later in life or have a short duration of deafness, as the brain is better able to interpret the signals.
how does coal and peat form
Saprotrophic bacteria and fungi will decompose dead organisms and return nutrients to the soil for cycling
This decomposition process requires oxygen (cell respiration is required to fuel digestive reactions)
Waterlogged regions may lack oxygenated air spaces within the soil and thus possess anaerobic conditions
Anaerobic respiration by organisms in these regions produces organic acids (e.g. acetate), resulting in acidic conditions
Saprotrophic bacteria and fungi cannot function effectively in anaerobic / acidic conditions, preventing decomposition
Since the organic matter is not fully decomposed in waterlogged soils, carbon-rich molecules remain in the soil and form peat
When deposits of peat are compressed under sediments, the heat and pressure force out impurities and remove moisture
The remaining material has a high carbon concentration and undergoes a chemical transformation to produce coal
how is oil and natural gas formed
Oil and natural gas form in anaerobic conditions at the bottom of seas and lakes when aquatic organisms die and are covered by layers of sediment, and are then compressed and heated.
explain the process of lactose free milk
Lactose is the sugar found in milk. It can be broken down by the enzyme lactase into glucose and galactose. However some people lack this enzyme and so cannot break down lactose leading to lactose intolerance. Lactose intolerant people need to drink milk that has been lactose reduced. Lactose-free milk can be made in two ways. The first involves adding the enzyme lactase to the milk so that the milk contains the enzyme. The second way involves immobilizing the enzyme on a surface or in beads of a porous material. The milk is then allowed to flow past the beads or surface with the immobilized lactase. This method avoids having lactase in the milk.
what are the advantages of lactose free milk
As a source of dairy for lactose-intolerant individuals
As a means of increasing sweetness in the absence of artificial sweeteners (monosaccharides are sweeter tasting)
As a way of reducing the crystallisation of ice-creams (monosaccharides are more soluble, less likely to crystalise)
As a means of reducing production time for cheeses and yogurts (bacteria ferment monosaccharides more readily)
what did watson and crick find
DNA strands are antiparallel and form a double helix
DNA strands pair via complementary base pairing (A = T ; C Ξ G)
Outer edges of bases remain exposed (allows access to replicative and transcriptional proteins)
what is a greenhouse gas
a gas in the atmosphere that causes the retention of heat in the atmosphere
what is the greenhouse effect
retention of heat from sun by the earths atmosphere
why is water vapor often left out on in greenhouse gases
amount of water vapor is related to temperature, dependent on other greenhouse gases
whats the purpose of valves in the heart
prevent the backflow of blood into the atria and ensure the blood flows in the correct direction
what organs digest lipids
pancreas and small intestine
amalyase digests starch into…
maltose
name the monosaccarides
glucose, fructose, galactose
can amalyse break down 1-6 amylopectin bonds
no!
what parts of digestive system secrete protein digesting enzymes into alimentrary canal
pancreas, stomach
name a function of intestinal epithelium
permeable to nutrients
form a barrier against harmful substances
provide large SA for nutrients (microvillus)
what type of bond does maltase break in maltose
glycosidic
state 2 functions of persetalsis in small inestine
mixes food with enzymes to aid digestion
moves food along the intestine
function of circular muscle
Contraction: When the circular muscles contract, they constrict the diameter of the lumen, effectively narrowing it.
function of longitudinal muscle
moves food forwrd within gut
define absorption
Digestion breaks down food into smaller, soluble molecules. These products of digestion then pass from the lumen of the intestine into the blood. They pass through the microvilli of the cell surface membrane and into the epithelium cells.
what functions of submucosa help with transport of absorbed substacnes
blood vessels, lymph vessels
draw the digestive system
what tissue layer develops into brain and spinal cord
ecotderm
what does notochord develop into
vertebrae
how are neurons removed
apoptosis
what does cerebellum do
unconscious functions such as balance and movement
what does brocas area do
speech and writing
purpose of enzymes in digestion
hydrolyses (breaks down) food
what ph does the stomach have, and why?
around 2 ph.
this is because its lined by gastric pits that release digestive juices
what cells in the stomach produce hcl
parietal cells
what is the purpose of hcl in the stomach
hcl activates pepsinogen into its active form, pepsin. it also helps kill bactdria and denatures proteins
name the 3 parts of the small inestine
duodenum, jejunum, ileum
state the difference between the 3 parts of the small intestine
duodenum - chemical digestion
jejunum - absorption of carbs, proteins, nutrients
ileum - absorbs any remaining nutrients, eg vitb12, bile salts
the main purpose of the large intestine is to absorb __ and __
water and electrolytes
why is there two sites for amalyase secretion - one in the salivary glands, and one in the pancreas?
because salivary amylase is denatured in the stomach. more amalyse is secreted into the chyme from the pancreas once it has passed the stomach
what does bile do
bile aids in the digestion of lipids, primarily triglycerides, through emulsification
whats the purpose of capillaries
exchange oxygen and nutrients in the blood with co2 and waste products from the cell
whats deamination
removal of amino acid groups from amino acids to create urea
whats exergonic
describe 4 processes needed for the spontaneous origin of life on earth
- synthesis of simple organic molecules from inorganic compounds
- assembly of these molecules into polymers
- formation of a polymer that can replicate
- packaging of these molecules into molecules into membranes with an internal chemistry different from surroundings
Describe the characteristics of stem cells that make them potentially useful in medicine.
a. stem cells are undifferentiated cells;
b. embryo cells are stem cells;
c. stem cells have/retain the capacity to divide;
d. can be used to produce cell cultures/large number of identical cells;
e. can be used to repair/replace damaged/lost cells/tissue;
f. stem cells are undifferentiated / have not yet differentiated/specialized;
g. can differentiate/specialize in different ways / are pluripotent/totipotent;
h. can be used to form a variety of different tissues / form organs;
i. used in medical research;
j. used in treatment of named disease;
k. stem cells are pluripotent
Discuss the advantages and disadvantages of the use of adult stem cells.
Advantages:
a. adult stem cells can divide endlessly / can differentiate
b. adult stem cells can be used to repair/regenerate tissues
c. fewer ethical objections than with embryonic stem cells
d. adults can give informed consent for use of their stem cells
e. adult source is not killed / source would not have grown into new human / no death of embryos used to provide stem cells
f. no rejection problems / patient’s own cells used
g. less chance of cancer/ malignant tumor development than from embryonic stem cells
h. most tissues in adults contain some stem cells
Disadvantages:
i. difficult to obtain/collect/find in adult body/very few available
j. some adult tissues contain few/no stem cells
k. adult stem cells differentiate into fewer cell types than embryonic cells /OWTTE
Explain how multicellular organisms develop specialized tissues.
a. only some genes are expressed in each cell type/tissue;
b. tissues therefore develop differently/become differentiated;
c. example would be goblet cell
Outline the functions of Rough Endoplasmic Reticulum and Golgi Apparatus:
Ribosomes on the Rough ER synthesize polypeptides for secretion and use outside of the cell. The golgi apparatus performs the function of modifying or altering the proteins. These proteins are secreted out of the golgi in vesicles, which transport them to the protein membrane.
Describe the process of endocytosis.
The membrane is principally held together by weak hydrophobic associations between the fatty acid tails of phospholipids
This weak association allows for membrane fluidity and flexibility, as the phospholipids can move around to some extent
This allows for the spontaneous breaking and reforming of the bilayer, allowing larger materials to enter or leave the cell without having to cross the membrane (this is an active process and requires ATP hydrolysis)
The process by which large substances (or bulk amounts of smaller substances) enter the cell without crossing the membrane
An invagination of the membrane forms a flask-like depression which envelopes the extracellular material
The invagination is then sealed off to form an intracellular vesicle containing the material
There are two main types of endocytosis:
Phagocytosis – The process by which solid substances are ingested (usually to be transported to the lysosome)
Pinocytosis – The process by which liquids / dissolved substances are ingested (allows faster entry than via protein channels)
What is the difference between absorption spectrum and action spectrum for photosynthesis?
The action spectrum represents the rate of photosynthesis at each wavelength of light while the absorption spectrum shows the percentage of light absorbed at each wavelength.
Name one type of fossil fuel that was formed from partial decomposition of organic matter at the bottom of lakes and oceans millions of years ago.
oil
crude oil
gas
natural gas
petroleum
coal
Coal
methane
Methan
What name is given to the membrane potential that must be reached in order for an action potential to be triggered?
threshold potential
threshold
threshold of excitation
Explain the reasons for the reclassification of Prokaryotes and Eukaryotes into Eubacteria, Archaea and Eukaryota.
studies of (base sequences of) rRNA provided evidence for three domain classification;
differences in cell walls / Archaea and Eukaryotes have no peptidoglycan in cell wall, Eubacteria do have peptidoglycan in cell wall;
differences in membrane bonding compared to Eubacteria and Eukaryotes / Archaea have ether bonds in lipid membranes whereas others do not;
presence or absence of histone proteins / histone proteins present in all Eukaryotes, present in some Archaea, none in Eubacteria;
large diversity of the group categorized as prokaryotes prompted division into two domains;
similarities between Archaea more similar to Eukaryota than to Eubacteria;
facilitates study of origin/evolution of eukaryotes;
Distinguish between Archaea and Eukarya.
a. membrane-bound organelles present in Eukarya but absent in Archaea;
b. 70S ribosomes in Archaea whereas 80S ribosomes in (cytoplasm of) Eukarya;
c. nuclear envelope in Eukarya, not in Archaea;
d. introns are present in Eukarya but only in some genes of Archaea;
e. histone proteins present in all Eukarya but only in a few Archaea;
f. the membrane lipid structure is unbranched in Eukarya but branched in Archaea;
g. Archaea can inhabit extreme habitats while Eukarya cannot;
Outline how leptin controls appetite.
a. leptin suppresses/inhibits appetite
b. is secreted by adipose tissue
c. level is controlled by amount of adipose tissue/ongoing food intake
d. leptin targets cells in hypothalamus which is the appetite control centre in brain
e. causes hypothalamus to inhibit appetite
f. if amount of adipose tissue increases, blood leptin concentration rises
Outline the unconscious control of the heart rate.
heart can contract without nervous stimulation/myogenic contractions;
SA node is pacemaker/generates heart beat/initiates each cardiac cycle;
stimulates atria to contract;
leading to contraction of ventricles;
nerves carry impulses from the brain to speed up and slow down the heart;
medulla of the brain monitors blood pressure;
epinephrine/adrenalin produced by adrenal gland
carried by blood to the heart
speeds up the heart rate;
autonomic/sympathetic and parasympathetic nervous system control;
sympathetic speeds up heart rate;
parasympathetic/vagus nerve slows heart rate back to normal/resting rate ;
Define tidal volume and ventilation rate.
a. tidal volume: volume of air taken in with each inhalation/out with each exhalation;
b. ventilation rate: number of inhalations/exhalations/breaths per minute;
Explain how an impulse passes along the axon of a neuron.
a. resting potential is –70mV / relatively negative inside in comparison to the outside;
b. Na+/K+ pumps maintain/re-establish the resting potential ;
c. more sodium ions outside than inside when at the resting potential;
d. more potassium ions inside than outside;
e. nerve impulse is an action potential that stimulates a wave of depolarization along the membrane/axon;
f. if neuron is stimulated/threshold potential/–50mV is reached sodium ion channels open;
g. sodium ions diffuse/move in;
h. Na+ move in causing depolarization;
i. potassium ion channels open / potassium ions diffuse/move out;
j. inside becomes negative compared with outside / potential across membrane restored / repolarization;
k. active transport of K+ into neuron and Na+ out of neuron restores resting potential;
l. Na-K pumps restore Na/K balance/resting potential
m. Myelin around the neuron insulates the axon
n. speeds the transmission
o. Myelin permits saltatory conduction
p. permits jumping from node to node
Membranes of pre-synaptic and post-synaptic neurons play an important role in transmission of nerve impulses. Explain the principles of synaptic transmission.
a. synapse is gap between adjacent neurons;
b. arriving action potential depolarizes pre-synaptic membrane;
c. opens voltage-gated calcium channels in membrane;
d. causes influx of calcium ions;
e. causes synaptic vesicles to fuse with pre-synaptic membrane;
f. vesicles release/exocytose neurotransmitter into the synaptic cleft;
g. neurotransmitter diffuses/moves across synaptic cleft;
h. neurotransmitter binds to receptors on post-synaptic membrane;
i. change in membrane permeability;
j. sodium ions flow into post-synaptic neuron;
k. opens channels allowing sodium ions/potassium ions to diffuse;
l. initiation of action potential/depolarization in post-synaptic membrane;
m. removal of the neurotransmitter; by enzyme / cholinesterase;
n. inactivated neurotransmitter returns to pre-synaptic neuron;
o. stops effect on post-synaptic membrane;
compare contrast rod and cone cells
rod
dim light
absorb all visible wavelengths
spread out throughout retina
One neuron connects many rods.
cone
Three types of cone cell (red, green, blue) absorb different groups of wavelengths
bright light
Concentrated in the centre of the retina.
One neuron connects to one cone cell
State the four main areas of the cerebral cortex, and outline their functions
Frontal lobe Regulates higher intellectual functions and controls social behaviours.
Occipital lobe Responsible for input from the eyes and judging distance and perspective.
Temporal lobe Involved in the regulation of speech, memory and hearing.
Parietal lobe Responsible for movement, spatial awareness and the sense of touch.
Explain how a doctor is able to diagnose brain death.
brain death is the medical definition of death;
doctors determine whether it is possible to preserve the life of the patient;
doctors will carry out more than one test to determine if treatment is possible;
without brain stem function, it might not be possible for the patient to live;
doctor will test pupil reflex by shining light into the eye of the patient;
if pupils do not constrict then this is a sign that the medulla oblongata may be damaged;
doctor may also observe any of the following: blinking response, the gag reflex, eye movement when the head is moved.
explain sypmpathetic/parasympathetic nerves for pupils in response to light
In bright light, parasympathetic nerves trigger circular muscles to contract and cause the pupils to constrict
In dim light, sympathetic nerves trigger radial muscles to contract and cause the pupils to dilate
define brain death
Brain death is defined as the permanent absence of measurable activity in both the cerebrum and brainstem
label and draw eye
Discuss the relationship between one gene and one polypeptide.
DNA codes for a specific sequence of amino acids. The DNA code for one protein is a gene. DNA is transcribed into mRNA. mRNA moves to a ribosome where it is translated into a polypeptide. Originally it was thought that one gene always codes for a polypeptide. Some genes do not code for a polypeptide. Some genes code for a transfer RNA and some sections of DNA code for regulators that are not polypeptides. Change in the gene structure will affect the primary structure of the polypeptide.
Describe the relationship between genes, polypeptides and enzymes.
gene is a sequence of DNA bases;
DNA/gene codes for a specific sequence of amino acids/polypeptide;
enzymes are proteins/composed of polypetides;
sequence of amino acids determines tertiary structure/folding/shape of active site;
change in the gene/mutation will affect the active site/function of an enzyme;
enzymes are involved in replication/transcription of genes;
enzymes are involved in synthesis of polypeptides;
Explain why DNA must be replicated before mitosis and the role of helicase in DNA replication.
two genetically identical nuclei/daughter cells formed during mitosis so hereditary information in DNA can be passed on ;
two copies of each chromosome/DNA molecule/chromatid needed;
helicase unwinds the DNA/double helix;
to allow the strands to be separated;
helicase separates the two complementary strands of DNA;
by breaking hydrogen bonds between bases;
state 3 exceptions of cell theory and why
Giant Algae: one multi-nucleated cell that grows to a large size without separate cells.
Striated Muscle Fibres: large multi-nucleated fibre formed from fusion of muscle stem cells
Fungal Hyphae: Aseptate hyphae that do not contain cross walls.
Rubisco, insulin, immunoglobulins, rhodopsin, collagen and spider silk protein functions
Structure
Collagen: A component of the connective tissue of animals (most abundant protein in mammals)
Spider silk: A fiber spun by spiders and used to make webs (by weight, is stronger than kevlar and steel)
Hormones
Insulin: Protein produced by the pancreas and triggers a reduction in blood glucose levels
Glucagon: Protein produced by the pancreas that triggers an increase in blood glucose levels
Immunity
Immunoglobulins: Antibodies produced by plasma cells that are capable of targeting specific antigens
Transport
Haemoglobin: A protein found in red blood cells that is responsible for the transport of oxygen
Cytochrome: A group of proteins located in the mitochondria and involved in the electron transport chain
Sensation
Rhodopsin: A pigment in the photoreceptor cells of the retina that is responsible for the detection of light
Movement
Actin: Thin filaments involved in the contraction of muscle fibres
Myosin: Thick filaments involved in the contraction of muscle fibres
Enzymes
Rubisco: An enzyme involved in the light independent stage of photosynthesis
outline the Changes to the Earth’s atmosphere, oceans and rock deposition due to photosynthesis
Oceans
Earth’s oceans initially had high levels of dissolved iron (released from the crust by underwater volcanic vents)
When iron reacts with oxygen gas it undergoes a chemical reaction to form an insoluble precipitate (iron oxide)
When the iron in the ocean was completely consumed, oxygen gas started accumulating in the atmosphere
Atmosphere
For the first 2 billion years after the Earth was formed, its atmosphere was anoxic (oxygen-free)
The current concentration of oxygen gas within the atmosphere is approximately 20%
Rock Deposition
The reaction between dissolved iron and oxygen gas created oceanic deposits called banded iron formations (BIFs)
These deposits are not commonly found in oceanic sedimentary rock younger than 1.8 billion years old
This likely reflects the time when oxygen levels caused the near complete consumption of dissolved iron levels
As BIF deposition slowed in oceans, iron rich layers started to form on land due to the rise in atmospheric O2 levels
Biological Life
Free oxygen is toxic to obligate anaerobes and an increase in O2 levels may have wiped out many of these species
Conversely, rising O2 levels was a critical determinant to the evolution of aerobically respiring organisms
visible light has wavelengths between..
400-700 nanometers
whats the role of bacteria in nutrient cycling
they act as decomposers and convert nutrients into accessible forms to humans and animals
whats the role of fungi in nutrient cycling
fungi are saprophytes
decomposers
returning nutrients to soil, converting it accessible to animals/ppl
whats the role of plants in nutrient cycling
add their own decaying matter to soils
absorb nutrients in soil and make avaliabel to browsing animals
whats the role of animals in nutrient cycling
break down nutrients from bacteria, plants, fungi
return nutrients via waste
