BIO UNITS 1&2 EXAM S2

domains

Archaea, bacteria, eukaraya

kingdoms

1. Animalia - multicellular (coral)

2. Archaea - unicellular (aeropynum pernix)

3. Bacteria - unicellular (eschoricha coli)

4. Fungi - uni or multicellular (yeast, mold, mushrooms)

5. Plantae - multicellular (moss, ferns)

6. Protista - uni or multicellular (algae)

Prokaryotic vs eukaryotic cells

BOTH

• plasma membrane

• cytosol

• ribosomes

• DNA

PROKARYOTES

• lack a nucleus

• have a single loop of DNA

• may contain some circular units of DNA called plasmids

• only unicellular

• reproduce through binary fission

EUKARYOTES

• contains many membrane-bound organelles

• contains multiple linear chromosomes of DNA in nucleus

• tend to be larger the prokaryotes

• uni or multicellular

• reproduce through mitosis and meiosis

Nucleus

surrounded by a double membrane

protects and confines genetic info (DNA)

inside is the nuclelous - site of ribosome production

ribosomes

tiny structures made or ribosomal RNA (rRNA) and proteins

either float freely in the cytoplasm or attatch to the RER

assemble the building blocks to make protein

rough endoplastic reticulum

a chain of connected and flattened sacs coated with ribosomes

this allows it to synthesize and modify proteins

typicaly surrounds or is close to the nucleus

smooth endoplastic reticulum

a chain of connected & flattened sacs, not coated in ribosomes

responsible for the production of lipids

golgi apparatus

stacked flattened sacs

site of protein sorting, packaging and modification

protein-filled vesicle often fuse with or bud from golgi body

mitochondria

site of aerobic cellular respiration which is a necessary process for all organisms to break down sugars into energy

contains an outer membrane surrounding a highly folded inner membrane'

• cellular respiration: C6H12O6 + 6O2 → 6CO2 + 6H20 + 36ATP

chloroplast

found in plant and algae cells

the site of photosynthesis

made of an inner and outer membrane

• photosynthesis - the process that uses light energy from the sun to produce oxegyn and glucose. 6CO2 + 6H20 → C6H12O6 + 6O2

SA:V ratio

a greater SA:V ratio can help a cell exchange materials efficiently with their environment.

• to increase you can either decrease their size or alter their shape (villi, microvilli)

phospholipid bilayer

the double layer of phospholipid molecules that makes up the cell membrane

• phosphate head: made of glycerol & phosphate group, negativly charged, hydrophillic, polar

• 2 fatty acid tails: made of long chains of carbon & hydrogen, uncharged, hydrophobic, non-polar

plasma membrane

controls the transport of substances in & out of the cell. selectivly permeable. all cells have one

plasma membrane - proteins

• integral - permanent part of the membrane

• transmembrane - proteins that span the entire bilayer

• peripheral - temporarily attatched to the membrane

functions

• transport - channels/pumps that controls what enters/exits the cell

• communication - cell-cell communication

• adhesion - sticks to other cells

plasma membrane - cholesterol

lipid steroid that embeds itself between the tails of bilayers in animal cells

function - regulates fluidity or membrane. at higher temps, the cholesterol keeps phospholipids bound together. at lower temps, it disrupts the tails, stopping phospholipids from becoming a solid boundary

simple diffusion

occurs when molecules move from an area of high concentration to one of low concentration (down the concentration gradient).

this leads to an even dispersion of particles

must be nonpolar, uncharged, hydrophobic, small (O2, H2, CO2, lipids, not ions)

facilitated diffusion

the passive movement of molecules down their concentration gradient through a membrane-bound protein. This allows large/polar molecules (glucose, ions) to move between the intra/extracellular environments via the use of a protein channel or carrier protein

protein channel

pores/holes in the membrane that allow a specific substance through

carrier proteins

bind to the substance thats being transported and undergos conformational change to push the substance down its concentration gradient through to the other side of the membrane

osmosis

the diffusion of water across a selectively permeable membrane from areas of low solute concentration to areas of high concentration

water molecules can move through the bilayer despite being hydrophillic as theyre small

hypertonic solutions

have comparativly high solute concentrations so water moves into a hypertonic solution from adjacent areas with lower solute concentrations

isotonic solutions

have equal solute concentrations so theres no net movement of water

hypotonic solutions

have comparatively low solute concentrations so water moves from a hypotonic solutions into adjacent areas with a higher solute concentration

bulk transport

involves transporting large molecules of groups of molecules (amino acids, proteins) in/out of a cell using vesicles

• exocytosis

• endocytosis

exocytosis

the process by which contents of a vesicle are released from a cell

1. vesicular transport - vesicle containing secretory products is transported to the plasma membrane

2. fusion - the membranes of the vesicle and cell fuse

3. release - the secretory products are released from the vesicle and out of cell

endocytosis

involves transporting large molecules or groups of molecules into the cell

1. fold - the plasma membrane folds inward to form a cavity that fills with extracellular fluid & the target molecules

2. trap - the plasma membrane continues folding back on itself until the 2 ends of the membrane melt and fuse. this traps the target molecule inside the vesicle

3. bud - the vesicle (or endosome) pinches off from the membrane. it can be transported to the appropriate cellular location or fused with a lyosome for digestion

phagocytosis

cell eating

endocytosis of solid materals/food particles

pinocytosis

cell drinking

endocytosis of engulfing molecules dissolved in extracellular fluid

binary fission

prokaryotes such as bacteria reproduce exponentially via binary fission which produces 2 genetically identical copies of a cell. asexual reproducion

DNA replication

Elongation
Septum formation
Cell division

interphase

the first and longest stage of the cell cycle. the cell synthesises neccesary DNA, proteins and organelles required for growth and replication. has 3 substages + G0

Gap 1 (G1) - intephase

the cell grows by increasing the volume of its cytosol, synthesising DNA for replication and replicating its organelles.

Gap 0 (G0) - intephase

are either quiescent or terminally differentiated

• quiescent - dormant, can re-enter cell cycle

• terminally differentiated - remain in G0 indefinetly

Synthesis (S) phase - intephase

cell replicates its DNA turning 1 chromosome into 2 genetically identical sister chromatids

Gap 2 (G2) - intephase

final stage where the cell continues to grow & prepare for mitosis, involves increasing the volume of cytosol and synthesizing proteins

mitosis

the second stage of the cell cycle and involves the seperation of the newly replicated chromosomes into 2 new nuclei

prophase - mitosis

• chromatin are visible under microscope

• centrioles migrate to opposite ends of cell

• spindle fibres begin to form

• nucleur membrane breaks down, nucleolos disappears

metaphase - mitosis

• spindle fibres fully form

• attatch to centromere of each chromosome

• fuides chromosomes to line up in equator of cell

anaphase - mitosis

• spindle fibres contract

• pulls sister chromatids to ends of cell

telophase - mitosis

• chromosomes pack together at ends of cell

• new nucleur membrane forms. 2 new nuclei form

• spindle fibres disintegrate & chromosomes decondense

• cleavage furrow forms

cytokinesis - mitosis

cell seperates into 2 genetically identical daughter cells

regulation of cell cycle

has 3 checkpoints where the cell inspects for errors before proceeding to the next stage. if errors are detected the cell can pause for repairs of undergo programmed cell death

• G1 checkpoint

• G2 checkpoint

• metaphase checkpoint

G1 checkpoint

verifes that a cell has:

• grown to correct size

• synthesized enough protein for DNA replication

• checks if DNA has been damaged during mitosis and cell growth

• checks if theres enough nutrients & oxegyn

G2 checkpoint

ensures that DNA has replicated properly in S phase and that cell has enough resources for mitosis

metaphase checkpoint

checks the formation of spindle fibres

apoptosis

the natrual and controlled death of cells within our body. there are 2 pathways

1. mitochondrial pathway

2. death receptor pathway

The mitochondrial pathway

when internal components (DNA) are damaged, mitochondria detect this & release cytochrome C into cytosol. this binds with cytosilic proteins for form an apoptosome which activates caspase enzymes, initiating apoptosis

The death receptor pathway

death signalling molecules are recognised by death receptor proteins on surface of cells (immune cells) when the molecules bind, caspase enzymes are activated, initiating apoptosis

necrosis

another way cells die. unregulated death of cells irriated by significant damage, causing the cell to burst, creating damage to other cells too.

apoptosis stages

after the activation of caspases and initiation of apoptosis

1. activation of caspases - internal DNA damage is detected and caspase enzymes are activated

2. digestion of cell contents - caspases cleave intracellular proteins, leading to the breakdown of organelles

3. cell shrinks - the cell & nucleus shrink as intracellular material is broken down

4. membrane blebbing & breakage - as the cytoskeleton is digested, the structural integrity of the cell is weakened. the membrane warps & detatches from the cell in membrane enclosed vesicles known as which contain the broken down intracellular material (apoptopic bodies)

stem cells

undifferentiated cells with the capability of differentiating into specialised cells with a particular function

potency

measures a stem cells capacity to differentiate into different cell types

• totipotent - stem cells that can differentiate into any cell type (zygote)

• pluripotent - stem cells that can differentiate into multiple cell types (embroynic stem cells)

• multipotent - stem cells that can differentiate into a limited number of specialised cell types (bone marrow)

self renewal

stem cells have the capacity to replicate without disrupting their ability to differentiate by producing both a differentiated cell and a copy of themselves when they replicate

transpiration

water & nutrients move up the xylem. only 1% of water from the xylem is used during photosynthesis. the remaining water evaporates & exits the leaf via the stomata during gas exchange

cohesion

the air pressure in the leaf becomes lower then the pressure in the roots. this creates a force that draws water up from the xylem. water likes to stick together so more is drawn up

adhesion

a force called capillary action help water flow from the xylem. capillary action is caused by the adhesion of water molecules to the surface of the xylem

conditions that affect transpiration rate

• temp - at higher temps, more water evaporates from the leaves

• light - in high light conditions, stomata can open to increase amount of CO2 absorbed for photosynthesis, further increasing the amount of water lost

• humidity - as humidity increases, less water can evaporate into the air

• wind - on calm days, water released from stomata stays close to the leaf. on windy days, the humid layer is blown away, encouraging water vapor to exit the leaf

• water availability - when its high, the roots absorb more water. the plant can then afford more to increase the rate of transpiration & lose more water

physical digestion

describes the process whereby mechanical movement or organs and tissues causes this breakdown of food into smaller pieces.

• such as: chewing, muscular contractions, stirring of food

• to be absorbed, food must first be broken into smaller pieces to provide a relativly large SA for digestion

chemical digestion

food pieces undergo chemica digestion by enzymes and stomach acid, producing smaller molecules that are capable of being absorbed

• the 3 major digestive enzymes: amylases, proteases, lispases

• most digestive enzymes split food molecules in hyrolysis reactions by adding water molecules

excretory system

the purpose is to remove excess & unwanted substances from the body & maintain a stable internal environment

kidney

2 bean-shaped organs that filter blood, reabsorb useful subastances within the filtrate and secrete unwanted ones

nephrons

a functional unit of the kidney consisting of a glomerus and tubule system through which a filtrate passes & urine is produced

endocrine system

responsible for producing hormones. a major group of signalling molecules that have a variety of effects throughout the body

hypothalmus

a small region in the brain that helps maintain body temp and often influences the function of the pituitary gland

pituitary gland

a pea sized area in the brain and is the ‘master gland’ as it regulates many other glands including the thyroid and adrenal glands, ovaries and testes.

thyroid gland

several small glands located in the base of the neck that are involved in controlling the growth rate, metabolic rate and development of the body

homeostasis

a complex process that maintains the internal environment of an organism within set limits so cells and systems can function properly

stimulus response model

outlines how changes in the ex/internal environement can influence an organisms functions.

1. stimulus - a change in the in/external environement of an organism

2. receptor - the stimulus is detected by a receptor in the body which transfers this stimulus into a chemical or electrical signal for transmission to the modulator

3. modulator - information from the receptors is sent here & compares this to a set point for a given variable

4. effector - a molecule, cell or organ that responds to a signal from the modulator and produces a response

5. response - any change in the function of a target cell, organ or organism after stimulation from an initial signal.

types of receptors

• thermoreceptors - detect changes in temp

• nociceptors - detect painful stimuli

• barorecepters - detect changes in pressure

• chemoreceptors - detect changes in chemical concentration

• photoreceptors - dectect changes in light

negative feedback system

occure when the response counters the stimulus. the response attempts to revert the system back to the state it was in before the stimulus occurs

temp regulation negative feedback loop

1. stimulus - change in core body temp or environment temp

2. receptor - thermoreceptors

3. modulator - hypothalmus

4. effector - see later

5. response - change in heat transfer to help maintain a core body temp of 37C

too hot - effector/response

• sweat glands - produce sweat which evaporates from skin, taking heat energy with it

• small blood vessels - vasodilate increasing surface blood flow so heat lost is increased (conduction/convection)

• cerebral cortex - causes changes in behaviour, seek shade

• arrector pilli muscles - relax which flattens body hair against skin, increasing heat lost to convection

• cells - signals are sent to slow metabolic processes, reducing amount of heat made by body

too cold - effector/response

• skeletal muscles - stimulated to cause shivering, creating more heat energy

• small blood vessels - vasoconstrict, decreasing surface blood flow so less heat is lost to environment

• cerebral cortex - causes changes in behavious, put on more clothes

• arrector pilli muscles - in the skin contract, lifting hair follicles up & trapping a layer of hair

• cells - signals are sent to increase metabolic processes, results in more heat energy being produced.

blood glucose regulation - negative feedback loop

1. stimulus - a charge in blood glucose levels to above/below 5mmol/L

2. receptor - alpha/beta cells

3. modulator - islets of langerhans

4. effector - see later

5. response - an increase/decrease in blood glucose levels to within normal limits

hyperglycaemic

to high, harms the body. response:

• skeletal muscle + fat cells - absorb more glucose from blood via the insertion of glucose transporters into cell membrane

• liver cells - stimulated to convert more glucose into glycogen

hypoglycaemic

too low, cells dont have enough energy to function properly

• liver cells - break down glycogen into glucose & release it into bloodstream via glycogenolysis

osmoregulation

regulating water balance helps prevent lysis (swell) or crenation (shrink)

1. stimulus - a change in the osmolality of blood or a change in blood volume and pressure, caused by a change in the volume of water in the body

2. receptor - osmoreceptors or baroreceptors

3. modulator - hypothalmus/pituitary OR cells in the kidneys

4. effector - cells in the distal convoluted tubule and collecting duct OR hypothalmus

5. response - returns rhe amount of water in blood to set point

type 1 diabetes

an autoimmune disease in which the bodies immune system recognises beta cells in the pancreas as non-self & attacks them using autantibodies. as a result, little or no insulin is produced (insulin replacement therpay/insulin pump)

• hyperglycaemia - above the normal range

• hypoglycaemia - below the normal range

type 2 diabetes

caused when the beta cells dont produce enough insulin. caused by a combination of genetic and lifestyle factors

the thyroid gland

a small butterfly gland located in the base of the neck & is part if the endocrine system. secretes 2 hormones:

• Triiodothyronine (T3)

• thyroxine (T4)

negative feedback loop of hyper/hypothyroidism

1. stimulus - change in a variety of factors (temp)

2. receptor - hypothalmus

TRH

3. modulator - anterior pituitary gland

TSH

4. effector - thyroid gland

5. response - release of T3 + T4

hyperthyroidism

a condition where the thyroid gland produces too much T3 + T4 symptons:

• basal metabolism - increased metabolism, heat intolerance, sweating

• nervous system - anxiety, irritability, difficulty sleeping

• cardiovascular system - increased heart rate, palpatations, increased blood pressure

• respiratory system - increased respiratory rate

hypothyroidism

the thyroid gland produces reduced levels of hormones. symptoms:

• weight gain

• reduced energy levels

• feeling cold

• poor memory + attention

structure of a chromosome

telomeres - protects end of chromosomes from fusing with others

centromere - a specialised sequence of DNA that holds them tg

DNA molecule - composed of a long DNA molecule thats been coiled tightly around histone proteins

homologous chromosomes

we call each of the sets of 23 chromosomes a pair of homologous chromosomes. criteria:

1. must have the same size and length

2. must have the same centromere position

3. share the same genes at the same gene loci

autosome/sex chromosomes

autosome: 1-22 (contain the genetic info for many genes)

sex: 23 (determines the sex)

karyotypes

a visual representation of an individuals entire genome organised into homologous pairs

chromosome variation

there is a chromosomal variation across organisms both within and across multiple species. this helps scientists recognise abnormalities

aneuploidy

a chromosomal abnormality with more or less missing chromosomes

• monosomy - has 1 missing chromosome (2n - 1)

• trisomy - has 1 extra chromosome (2n + 1)

• tetrasomy - has 2 exra chromsomes (2n + 2)

polyploidy

an organism has more than 2 sets of chromosmes (3n=72)

meiosis

a single diploid cell divides twice to produce 4 unique haploid daughter cells, each with half the number of chromosomes then the original. occurs in sexually reproducing organisms.

• meiosis I - seperates each homologous chromosome into 2 different cells

• meiosis II - seperates each sister chromatid into 4 different cells

crossing over

prophase I

exchanges DNA through swapping at the chiasma

independent assortment

metaphase I

lines up randomly along the equator

alleles

not all alleles of a gene are expressed equally

• homozygous - if an individual inherits 2 identical alleles (AA,aa)

• heterozygous - an individual with 2 different alleles (Aa)

complete dominance

when a dominant allele is fully expressed in a phenotype and masks the expression of a recessive allele. although a dominant allele may mask a recessive allele, heterozygous individuals can carry the recessive allele

codominance

occurs when both alleles from the genotype are fully expressed in the phenotype if a heterozygote (both alleles can be thought of as dominant)

incomplete dominance

occurs when neither allele from the genotype is fully expressed in the phenotype of a heterozygote and the resulting observable trait is a ‘blending’ of both alleles

epigenetic

changes to an organisms phenotypes resulting from modificationsn to gene expression, due to the environment or phenotype

DNA methylation - epigenetic factors

occurs when methyl groups attatch to certain nucleotides within the DNA sequence of a particular gene & alters gene expression, typically causing that gene to be silence

DNA demethylation - epigenetic factors

in contrast, refers to the removal of methyl groups from a DNA sequence & typically leads to a gene being exposed

histone modification - epigenetic factors

occurs when histone-modifying enzymes known as histone methyl transfers join methyl groups to histone tails & modify how tightly a DNA molecule is wrapped around it