end of year exam Flashcards
cell theory
- all organisms are made up of one or more cells
- all cells come from pre-existing cells
- cells are the basic unit of structure and function of living things.
prokaryotic cells
lack any membrane bound organelles including a nucleus
eukaryotic cells
cells that process membrane bound organelles as well as a nucleus that hold the genetic information
membrane bound organelles
a cellular structure that is bound by biological membrane that controls the movement of substances between the organelle and the cells cytosol allowing each organelle to have a different composition from the surrounding cytosol and other organelles.
plant cells v animal cells
plant cells have a cell wall and contain a large singular vacuole
benefits of compartmentalisation
- allows enzymes and reactions for a particular function to be close together high concentration in the right conditions, such as optimum pH levels, so that processes within the organelles are very efficient
- allows processes that require different environments to occur at the same time in the same cell.
- makes the cell less vulnerable to changes to its external environment, affecting the cytosol more than the membrane bound organelles
nucleus structure and function
structure- membrane bound-double membrane contains DNA function- contains hereditary information
rough endoplasmic reticulum structure and function
structure-
membrane bound-network of cisternae
function-
processes and modifies proteins
ribosome structure and function
structure-
made of proteins and rRNA
function-
synthesises proteins
smooth endoplasmic reticulum structure and function
structure-
membrane bound - networks of cisternae
function-
synthesises lipids
centrioles
a pair of small cylindrical structures composed of microtubules that are present in most eukaryotic cells and are involved in cell division and the formation of certain cell structures
phospholipids
hydrophobic tail and hydrophilic head that make up the bilayer of the plasma membrane
cell surface area to volume ratio
the surface area of the plasma membrane around he cella affect the rate of exchange that is possible between the cell and its environment and can affect
cytoplasm
gives cells its shape
cell membrane
controls what come in and out of the cell
mitochondria
produces ATP
Golgi
modifies, sorts and packs macromolecules that are synthesised by the cell
plasma membrane
controls movement between the extracellular fluid and the intracellular fluid (cytosol)
what can move through the bilayer
small molecules that are hydrophobic
- oxygen
- carbon dioxide
- colesterol
diffusion
passive (without energy) movement of molecules among a concentration gradient until they reach an equilibrium
facilitated diffusion
hydrophilic molecules (glucose) that cannot pass through the bilayer move through transport proteins that are in the membrane passive process and moves along concentration gradient until an equilibrium is reached
hypertonic
higher concentration in solute
hypotonic
lower concentration in solute
isotonic
equal concentration in solute
osmosis
diffusion of water across a membrane from an area of high water concentration to an area of low water concentration that move through portions called aquaporins and is a passive form of transport
polar molecules
uncharged overall however one end of the molecule is +vely charged and the other is -vely charged. other molecules that are polar can dissolve in water ie glucose polar molecules are hydrophilic
non polar molecules
no charged areas ie lipids other molecules that can dissolve in lipids are non polar non polar molecules are hydrophobic
surface area to volume ratio (SA:V)
as the cell gets larger the SA compared to the V decreases and vise versa
biomacromolecules
large molecules used by cells also known as polymers - molecules made up of many subunits (monomers)
CHO(N)
carbon, hydrogen, oxygen,(N)itrogen
CARBOHYDRATE
monomer - monosaccharides - glucose - fructose - B-galactsidose
polymer -
polysaccharides
- cellulose
- starch
CHN(P)
carbon, hydrogen, nitrogen (P)hosperous
PROTIEN
monomer
amino acid
polymer
proteins
CHO
carbon, hydrogen, oxygen
lipids
monomer
fatty acids (not usually a true monomer)
- glycerol
polymer
fats and oils (not usually a true polymer)
- phospholipids
CHONP
carbon, hydrogen, oxygen, nitrogen, phosphorus
monomer nucleodies - adenine - thymine - cytosine - guanine
polymer
nucleic acids
- DNA (deoxyribonucleic acid)
- RNA (ribonucleic acid)
photosynthesis
carbon dioxide + water → glucose + oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
adaptations
a genetically controlled structure, behaviour or physiological feature that enhances the survival and reproductive potential of an organism in particular environmental conditions
structural adaptations
physical features of organism (external) ie cold environment - more hair, hot environment - large ears (to release heat)
behavioural adaptations
the way organism act ie seeking shade or shelter, nocturnal
physiological adaptations
functional adaptations to do with the inner workings if the organism (internal) ie production of venom.
abiotic
non-living thins, not made of cells (rock, minerals)
biotic
living things or have lived (tree, wood)
tolerance range
for each environmental factors an organism has a tolerance rage in which it can survive (bell curve)
limiting factors
things that prevent a population form growing any larger. (temp. water, salt concentration.)
endotherm
internally generated heat to maintain body temperature
exotherm
rely on external heat source to maintain body temperature changes within their environment
receptor
a specialised structure that can detect a specific stimulus or initiate a response
control centre
feedback mechanism that determines the response required and sends an appropriate signal tot the effector
effector
a component in the feedback system that causes a change in order to reverse a situation to the normal range
negative feedback loop
a control response that works to maintain homeostasis by activating an opposite response tor return to a normal range
ADH
antidiuretic hormone - regulates water reabsorption it is synthesised in th hypothalamus and transported to the posterior pituitary gland where it is stored
acts on kidney to increase permeability to water
insulin
peptide hormone produced by beta cells in the pancreas regulates metabolism promoting the absorption of glucose within cells stimulates glycogen formation
glucagon
peptide hormone produced by alpha cells in the pancreas raises the concentration of glucose in the blood by
hormones
signalling molecules that are responsible for communication between organs to regulate physiological and behavioural processes
receptor molecules
molecules that bind to specific hormones - binding to the hormone/receptor initiates cellular effects to mediate a cellular response
hypothalamus
a region of the brain that receives information from all parts of the body’s condition used to regulate hormones from the pituitary gland
pancreas
responsible for releasing glucagon and insulin
cerebral cortex
ultimate control and information processing centre in the brain
vasoconstriction
the narrowing of the capillaries (a response to being cold)
vasodilation
the widening of the capillaries enhances blood flow to areas that lack oxygen/nutrients (response for being too hot)
glycogen
multi branch polysaccharide of glucose that serves as a form of energy storage
autotrophs
self feeders – able to make their own organic compounds using energy and inorganic compounds (carbon dioxide, water) which come from their physical environment to synthesis organic compounds
Heterotrophs
consumers – they obtain organic compounds from autotrophs or other heterotrophs
photoautotroph
- organism that obtain the energy required for carbon fixation from light or solar energy. Combine carbon dioxide and water using sunlight to produce organic compounds aka photosynthesis ie green plants, algae
Chemoautotroph
- obtain the energy they need for carbon fixation through inorganic chemical reactions (chemosynthesis).
cellular respiration
the process in which organisms transform chemical energy from organic compounds into ATP by breaking apart glucose lipids and proteins.
glycolysis
The first process that takes place in cellular respiration, involves the splitting of glucose into two pyruvate molecules this occurs in the cytosol and does not require oxygen (anaerobic). Uses two ATP in breaking down one glucose molecule, producong four more – net production of two ATP molecules.
aerobic respiration
Glucose + oxygen —> carbon dioxide + water + available energy
C6H12O6 + 6O2 —> 6CO2 + 6H2O
Light dependant photosynthesis
occurs in the thylakoid membranes of the chloroplast, process where photolysis occurs, water is split into hydrogen ions and oxygen gas
Light independent reaction
produce glucose water and ADP and do not require solar energy. Takes place in the stream of the chloroplasts
temp. affect on photosynthesis
all light dependant and light independent reactions are catalysed by enzymes, temperature increases the activity of enzymes however become denatured after the optimum temperature has been reached making the rate of photo synthesis decline rapidly. Optimum temperature differs per plant dependent on environmental factors
light affect on photosynthesis
When light intensity is low the light dependant reactions can not occur, therefore at night, light intensity is a limiting factor because photosynthesis cannot occur. As the light increases the rate of photosynthesis will increase, however at a certain level of light intensity the effect of the light will plateau
carbon dioxide affect on photosynthesis
Carbon dioxide is used to produce glucose like light the rate of photosynthesis will increase as there is more carbon dioxide is available, however will plateau once a maximum has been reached
carbon dioxide affect on photosynthesis
Carbon dioxide is used to produce glucose like light the rate of photosynthesis will increase as there is more carbon dioxide is available, however will plateau once a maximum has been reached
ATP
the universal carrier of energy in living organisms. Molecules of ATP are the immediately unusable chemical energy that is required for cell processes . It contains two high energy bond between the in organic phosphate groups, that can be easily broken to release a small amount of energy. This energy is used to carry out all the energy dependant processes of cells. When the molecule of ATP gives up its energy, it splits in to a molecule of ADP (adenosine triphosphate) and a molecule of phosphate. It can be recycled by the ADP to create ATP again from the breakdown of glucose during cellular respiration using much less energy tha if it were to make an entirely new ATP molecule.
stages of the cell cycle
- G1
- S
- G2
- MITOSIS
G1
the cell gains energy and undergoes metabolic processes such as protein and membrane synthesis - almost doubles in size
S
chromosome and DNA replication
G2
cell undergoes secondary stage of growth, metabolism and energy acquisition prepares for mitosis by synthesising proteins needed for division
Mitosis
- prophase
- metaphase
- anaphase
- telophase
- cytokenisis
prophase
dna finishes condensing and chromosomes become visible, centrioles move to opposite sides of the nucleus
metaphase
chromosomes line up in the middle of the cell
anaphase
splitting of the centromeres separated to opposite poles
telophase
nuclear membrane forms around the two sets of chromosomes that become thinner and longer
cytokinesis
the cell splits
cell cycle checkpoints
G1 checkpoint - the cell is large enough and their are enough organelles
G2 checkpoint - has DNA been replicated correctly
M checkpoint - have the spindle fibres been correctly attached to the DNA
chromosomes
complex structures consisting of DNA strands around histone proteins carrying the heredity information of the cell in the form of genes
centromere
part of the chromosome that attaches to spindle fibres during mitosis and where two sister chromatids of a double strand chromosome are joined
haploid
one individual chromosome for each chromosome type (n)
diploid
a homologous pair for each chromosome (2n)
embryonic stem cells
- relatively undifferentiated
- cells of embryos
- can be obtained from surplus 3-5 day old embryos from IVF programs
- can become many types of cells
- can replicate indefinitely
adult stem cells
- present in a small number of some adult tissues (hair follicles, bone marrow, spinal cord, germ cells)
- remain as stem cells through an individuals life - can give rise only to a limited range of cells
- the biological purpose is to repair and regenerate aged and ages tissue
- cannot replicate indefinitely
totipontecy
- capable of giving rise to any cell type
-
pluripotent
- differentiate into any of the germ layers
- present in blastocysts
- the primordial germ cells that give rise to gamets are also pluripotent
multipotent
- give rise to multiple but limited cell types
-
unipotent
- only differentiate into one cell type
- found in a specific tissue but can divide repeatedly
fission
- most common form of asexual reproduction
- occurs when a singular parent cell divides in to two approx. equal parts and each of them develop into a new organism
fission in unicellular organism occurs either by binary fission (prokaryotes) or mitosis (eukaryotes)
longitudinal fission
occurs when the cell splits along the longest axis
transverse fission
occurs when the cell splits across the shortest axis
strobilation
occurs in multicellular organisms
occurs in cnidarians and coral polyps
budding
new individual rises as an outgrowth or bud from the parent
occurs in yeast, small multicellular organisms such as hydra
vegetative propagation
growth if specialised plant tissue that can grow into a new plant if separated from the parent
rhizomes
stolons
meiosis interphase
- 4 chromsomes
- 2 homologous pairs
meiosis prophase I
- crossing over
- homologous pairs
meiosis metaphase I
- chromosome pairs align nuclear membrane breaks down
meiosis anaphase I
- homologous pair seperate
meiosis telophase I (cytokenesis)
- 2 daughter cells
- haploid
meiosis prophase II
- chromosome do not pair
meiosis metaphase II
- chromosomes line up in the middle
- nucleus dissolves
meiosis anaphase II
- chromosomes separate
meiosis telophase II
- 4 daughter cells
- haploid
heterozygous
two different alleles ie Pp
homozygous
both copies are the same alleles ie PP or pp
genes
a section of dna that contains a particular set of instructions that usually instructs the cell to produce a type of protein
allels
a version of a particular gene
dominant
only needs one copy of the alleles to express the trait
recessive
need both alleles to be expressed
genotype
combination of genes that carry the DNA
phenotype
the displayed gene (how it looks)
