Chapter 1 & 4 Understanding Flashcards
Rate of exchange of materials depends on what?
SURFACE AREA
Rate at which materials are being used / produced depends on what?
VOLUME
What is 1 advantage of being multicellular?
division of labour (differentiation)
How can SA:V ratio be maximised?
cell division
compartmentalisation
folding up
thin
narrow
spherical
Outline features of stem cells
- capacity to DIVIDE & DIFFERENTIATE along dif pathways
- self-renewal + potency
totipotent example
zygote
pluripotent
can differentiate into any cell found in embryo
- anything except extra-embryonic cells like placenta
multipotency
adult stem cells that can differentiate into closely related cell types
e.g. bone marrow –> dif blood cells
unipotency
adult stem cells that can dif. into their own lineage
- e.g. heart muscle cells, neuron
most cells are unipotent
Functions of life
metabolism
response
homeostasis
growth
excretion
reproduction
nutrition
What are advantages of compartmentalisation?
- enzymes / substrates concentrated in small area –> better metabolism
- pH & other conditions at optimum levels
- damaging substances isolated
Outline functions of membrane proteins
- hormone binding site
- immobilized enzyme (Catalyst)
- cell adhesion
- cell-to-cell communication (glycoprotein)
- channels for passive transport
- pumps for active transport
What is the function of cholesterol?
- controlling fluidity
- reducing permeability to hydrophilic substances
- prevents crystallisation
- helps membranes curve into concave shape
- formation of vesicles
Outline the process of exocytosis
- proteins synthesised by ribosomes –> enter rER
- vesicles bud off from rER
- carry proteins to Golgi apparatus
- Golgi apparatus MODIFIES proteins
- vesicles bud off from Golgi apparatus & carry modified proteins to plasma membrane
Outline the activity of cyclins
- groups of proteins that regulate timing of cell cycle –> progression to next stage
- cyclins bind to enzymes (cyclin-dependent kinases)
- kinases become active & attach phosphate groups to other proteins in cell
- phosphate triggers other proteins to become active & carry out tasks for that stage
- cyclins must reach threshold concentration to allow progression to next stage
- ensures cells only divide when needed
Distinguish b/w cytokineses in plants & animals
PLANTS:
- cell plate forms at equator
- new cell walls produced
ANIMALS:
- cleavage furrow forms
- separates daughter cells
- actin + myosin proteins form contractile ring under plasma membrane
- ring is formed at equator of cell
- plasma membrane pulled in
Universality of genetic code
64 codons of genetic code = same meaning in cells of organisms w/ small variations
Origin of 1st cells
- production of carbon compounds (e.g. sugars/amino acids)
- assembly of organic compounds into polymers
- formation of polymers that can self-replicate
- formation of membranes to package the organic material
Function of pilli
- shorter, thinner than flagella
- found in prokaryotes
- assist w/ movement
- conjugation (exchange of genetic material)
- adherence to surfaces
What is cell wall made of in plants?
polysaccharide cellulose
What is cell wall made of in most bacterial cells?
peptidoglycan
What is the flagella made of?
long microtubules
What is the role of centrioles?
- organise microtubules
- help determine location of nucleus + other organelles
- NOT FOUND IN FLOWERING PLANTS / FUNGI
What is the function of microtubules?
- support + movement
found in ALL EUKARYOTIC CELLS
Functions of life in paramecium
- nutrition –> endocytosis
- growth –> obtains nutrients from organic matter
- response –> beating of cilia
- excretion –> expels waste products of metabolism
- homeostasis –> expels water using contractile vacuoles
- reproduction –> reproduces asexually or sexually
- metabolism –> enzymes catalyse reactions
Functions of life in chlorella
- nutrition –> photosynthesis
- growth –> increase in size due to photosynthesis / absorption of minerals
- response –> chlorophyll pigments absorb light
- excretion –> oxygen diffuses out of cell
- homeostasis –> expels water using contractile vacuoles
- reproduction –> asexually or sexually
- metabolism –> enzymes catalyse reactions
Functions of life in chlorella
- nutrition –> photosynthesis
- growth –> increase in size due to photosynthesis / absorption of minerals
- response –> chlorophyll pigments absorb light
- excretion –> oxygen diffuses out of cell
- homeostasis –> expels water using contractile vacuoles
- reproduction –> asexually or sexually
- metabolism –> enzymes catalyse reactions
Magnification = ?
SIZE OF IMAGE / REAL-LIFE SIZE
Potassium channel in axons (facilitated diffusion)
- Open in response to depolarisation of axon membrane (+ inside)
- Allow K+ to exit via facilitated diffusion causes repolarisation
- Globular subunit closes the channel (“ball & chain”)
- Channel returns to original shape
Sodium-Potassium Pump (Active Transport)
- 3 Na+ ions from INSIDE of axon bind to pump
- ATP attaches to pump & transfers phosphate to pump
- Pump changes shape + opens to outside of axon
- 3 Na+ released, 2 K+ enter
- The attached phosphate is released, pump changes shape again
- K+ ions released inside, resting potential electrochemical gradient
Stargardt’s macular dystophy
- EYE
- Genetic disease in 6-12 year olds
- Recessive mutation of ABCA4 gene
- Membrane protein used in active transport in retinal cells malfunctions
- Photoreceptive cells degenerate
- Embryonic stem cells injected into eyes
- Cells attach to retina, differentiate into healthy retinal cells
Leukemia
- cancer in bone marrow
- mutations in genes resulting from over-production of white blood cells (leukocytes)
- Large needle inserted into bone
- Stem cells extracted + stored by freezing
- Adult stem cells only have potential for producing blood cells
- Chemotherapy kills all cancer cells in bone marrow
- Bone marrow loses ability to produce blood cells
- Stem cells (HSCs) returned to patient
- Produce healthy blood cells
Define oncogenesis
the formation of tumours
- starts w/ mutations in genes involved in controlling cell cycle
- chemicals (mutagens) cause mutations –> tumours
- metastasis: spreading of tumours from primary to secondary (from benign to malignant)
Why is mitosis needed?
- embryonic development
- growth
- tissue repair
- asexual reproduction
Outline events that occur in interphase.
- increase in mass + size
- carries out many cellular processes
- synthesises proteins
- replicates its DNA for mitosis
- increases # of mitochondria &/or chloroplasts
G1, S, & G2 phases
G1 phase: growth + cells make RNA, enzymes, & other proteins, signal received telling cell to divide
S phase: synthesis of DNA, short phase DNA in nucleus replicates, each chromosome consists of 2 identical sister chromatids
G2 phase: cell continues to grow, other preparations for cell division made
What is chromatin?
DNA molecules that are loosely coiled around histones (in eukaryotes) before prophase
- condenses during prophase
What are benign tumours?
do not spread from original site; do not cause cancer
What are malignant tumours?
- spread through body in blood, destroy and invade other tissues
- cause cancer
- interfere w/ normal functioning of organ
carcinogen
any cancer-causing agent
How does cancer arise?
due to uncontrolled mitosis
cancer cells divide repeatedly
starts when changes occur in the genes that control cell division (oncogene) –> due to mutation
define oncogen
a mutated genet that causes cancer
Mitotic index = ?
of cells w/ visible chromosomes / total # of cells
What does rate of diffusion depend on?
- steepness of concentration gradient
- temperature
- surface area
- properties of molecules/ions (e.g.. polarity, size)
Distinguish b/w channel & carrier proteins.
CHANNEL PROTEIN: water filled pores, allow charged substances through, most are GATED –> controls exchange of ions
CARRIER PROTEIN: can switch b/w 2 shapes, binding sites opens/closes on 2 sides, can be involved in BOTH active transport & facilitated diffusion, slower than channel proteins
Example of exocytosis
secretion of digestive enzymes from pancreatic cells
Define osmolarity
measurement of the solute concentration of a solution
- water moves from LOW to HIGH osmolarity
- # of SOLUTE particles per 1 L of solvent
What is plasmolysis?
Plasmolysis is the shrinking of protoplasm away from the cell wall of a plant or bacterium
spontaneous generation
the belief that life could appear in non-living material
Evidence to support endosymbiotic theory
- mitochondria / chloroplasts share w/ prokaryotes:
70S ribosomes
double membranes
binary fission
circular DNA
transcribing mRNA from DNA
Endosymbiosis
one organism lives within another - engulfed via endocytosis
Pasteur’s Experiments
- Used swan-necked flasks
- Microorganisms trapped in bend of neck
- Added nutrient broth to flasks + boiled them to sterilise
- Broke off the necks for some flasks
- After long time, broth in flasks w/ snapped necks –> cloudy
- Growth of microorganisms
- Broth in swan necks –> clear
- Swan necks prevented microorganisms in air from entering broth – organisms do not appear spontaneously (Despite contact w/ air)
Exocrine glands of pancreas
- FUNCTION: secrete digestive enzymes into pancreatic duct
- nucleus, rER, mitochondria, Golgi apparatus, vesicles (pancreatic digestive enzymes that will be released into duct), lysosomes
Palisade mesophyll cell
- FUNCTION: in plant leaves & structured to maximise the efficiency of leaf’s functions
- situated at TOP of leaf
- chloroplasts, permanent vacuole, cell wall
Evidence for Davson Danielli Model
- Proteins arranged in layers above + below phospholipid bilayer
- Membranes good at controlling movement into + out of cells
- e- micrographs showed membrane had 2 dark lines w/ lighter band in b/w
- proteins appear darker than phospholipids
- membranes –> partially permeable
- chemical analysis showed membranes consist mainly of proteins + lipids
Evidence for Fluid-Mosaic Model
- freeze-etched e- micrographs of centre of membrane showed globular structures
- had proteins that were hydrophobic (biochemical analysis)
- fluorescent markers of antibodies –> red + green mixed throughout the fused cell membranes
- fluid membrane; globular proteins; peripheral / intrinsic
Define resolution
the ability of the microscope to show 2 close objects separately in the image
Light microscope vs electron microscope
LIGHT: lower res, reveal structure, allows observation of tissues + LIVING cells in colour, only 1000x magnification, for larger structures / organisms
ELECTRONS: high res, beams of e- have much shorter wavelength, reveal ultrastructure, non-living specimen in black/white, 500,000 x mag, for very small structures / viruses
Saprotrophs (decomposers)
- EXTERNAL DIGESTION - secrete digestive enzymes into dead leaves, wood, feces
e.g. bacteria / fungi
Detritivores
- internal digestion - detritus
- detritus = dead material from living organisms including dead leaves, roots, feces
e.g. larvae of wax moth
consumers
- feed on living / dead organisms by ingestion
- organisms may be alive or dead
Energy Losses
- some organisms die before eaten
- some parts of organisms NOT eaten (hair, bones)
- some parts are INDIGESTIBLE (cellulose)
- cell respiration (lost as HEAT)
- energy losses between trophic levels limits the length of food chains
Why does biomass reduce along a foodchain?
- due to loss of CO2, water, & other waste products e.g. urea
- biomass is lost so that the ENERGY CONTENT per gram of the tissues of EACH SUCCESSIVE TROPHIC LEVEL is NOT LOWER
Methanogenic Archaeans
- prokaryotes that produce methane
- break down o-matter in ANAEROBIC, ACIDIC CONDITIONS
- release methane as waste product (in swamps / bogs)
- dead o-matter not fully decomposed by saprotrophic bacteria due to anaerobic conditions
- methane may accumulate in ground / diffuse into atm
- oxidised to CO2 & H2O
Peat / coal
- o-matter not broken down in acidic/anaerobic conditions
- partially decomposed plant matter accumulates
- thick deposits (peat) form
- in past geological eras, peat was crushed & converted into coal
Oil / gas
- silt is deposited on bed of shallow seas, along w/ remains of dead marine organisms
- o-matter only partially decomposed due to anaerobic conditions
- silt on seabed converted into shale, with compounds from o-matter becoming OIL OR GAS TRAPPED IN PORES IN ROCKS
Limestone
- made of CaCO3
- fossils, mollusc shells, skeletons of hard corals
- these organisms absorb calcium + carbonate ions & secrete them as CaCO3
- shells of marine molluscs fall to seas bed when die & become part of limestone rock
- skeletons of hard corals accumulate over time, gradually building coral reefs
- oceans absorb CO2, dissociates into H+ & HCO3- ions, reduced calcification
Energy vs Nutrients
- energy = continuous but variable supply of energy in the form of sunlight –> CANNOT but recycled
- nutrients = finite & limited –> CAN be recycled
What does the impact of a gas depend on?
- its ability to absorb long-wave radiation
- its concentration in the atmosphere
Why does changes in CO2 concentration follow Northern Hemisphere seasons?
- the area of land is GREATER
- CO2 concentrations are greater on land in sea
- DROP IN CO2 FROM MAY TO OCTOBER
Which unit is used to measure carbon fluxes?
gigatonnes
trophic level
the position of an organism in the food chain
unit for energy pyramids
kJ m^-2 year^-1
Energy sources
- light
- chemical energy when consuming producers
community
a group of populations of different species living together & interacting w/ each other in an area
food web
complex network of feeding relationships in a community
ecosystem
biotic + abiotic environment
Examples of combustion of fossil fuels
- in vehicles used for transport
- when homes are heated
- production of electricity
- burning of forests for clearing
Effects of global warming
- heavier rainfall
- rising seawaters
- decreases in ice habitats
- destroys coastal habitats
- change in species + migratory patterns
- competition b/w species
- increased rates of decomposition of detritus from (melting) permafrost
- increased success of pest species including pathogens
Quadrats
- square sampling area used in ecological research
- plants / animal species within the quadrat are identified & recorded
Mesocosms
- small experimental area setup in an ecological research program
- need autotrophs to produce carbon compounds & regenerate O2
- saprotrophs needed to decompose dead organic matter / recycle nutrients
- ## consumers + detritivores NOT needed, but are normal part of ecosystem
How to deduce CO2 concentrations & temperatures from the past.
- Columns of ice have been drilled in the Antarctic
- The ice had built up over thousands of years
- Ice from deep down is older than ice near the surface
- Bubbles of air trapped in the ice can be extracted & analyzed to find the CO2 concentration
- Global temperatures can be deduced from ratios of hydrogen isotopes in the water molecules
Organisms made of CaCO3
mollusca
crustacean
porifera
sponges
Discuss need for international cooperation to solve the problems of declining coral populations
- ocean currents / tides move CO2 & acid/heat around world
- coral reefs are in international waters
- sharing in tech / research / resources
- aid to poorer countries
- economic + ecological benefits
When is a cell NOT likely to divide?
- if already specialised / differentiated
- if nucleus is shown to be in interphase NOT in mitosis
Which features do plants lack?
centrioles
lysosomes
cilia
flagella
intermediate filament
Outline how greenhouse gases interact with radiation and contribute to global warming.
a. carbon dioxide is a greenhouse gas
b. methane/nitrogen oxide/water vapour is a greenhouse gas
c. sunlight/light/(solar) radiation passes through the atmosphere (to reach the Earth’s
surface)
d. CO2 in atmosphere/greenhouse gases absorb/trap/reflect back some radiation/heat
(emitted by the Earth’s surface)
e. CO2 in atmosphere/greenhouse gases allow short wave radiation to pass (through
atmosphere) but absorb long wave/infra-red
f. solar radiation/sunlight is (mostly) short wave
g. radiation/heat emitted by the Earth is long wave/infra-red
Describe the reasons for the shape of a pyramid of energy
a. pyramid of energy has stepped shape with largest bottom step being producers, then first consumer, second consumer, etc
b. light energy «from sun» converted to chemical energy in carbon compounds by photosynthesis
c. energy released by respiration is used in living organisms AND converted to heat
d. heat «energy» is lost from ecosystems
e. approximately 10 % of energy in trophic level converted into new material for next level
f. energy also lost as undigested material/uneaten material/feces/excretion
