B1 - key concepts in biology Flashcards
what are the two types of cell
eukaryotic and prokaryotic
difference between eukaryotic and prokaryotic cells
- eukaryotic: plants and animal cells, membrane bound organelles
- prokaryotic: bacteria, unicellular organism
what is a eukaryote
an organism made up of eukaryotic cells
what is a prokayote
a prokaryotic cell, single celled organism
subcellular structures of animal cells
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
subcellular structures of plant cells
- same as animal cells, as well as:
- cell wall
- large vacuole
- chloroplasts
subcellular structures of bacterial cells
- chromosomal DNA
- ribosomes
- plasmid DNA
- flagellum
- cell wall
- cytoplasm
function of nucleus
- contains genetic info
- controls activity of cell
- genetic info arranged into chromosomes
function of cytoplasm
- where most chemical reactions occur
- contains enzymes that control chemical reations
function of cell membrane
- holds cell together
- controls what goes in and out
function of mitochondria
- where respiration occurs (aerobic)
- respiration transfers energy the cell needs to work
function of ribosomes
- involved in translation of genetic material and protein synthesis
function of cell wall
- made of cellulose (only in plants)
- supports and strengthens the cell
function of large vacuole
- contains cell sap (weak mix of sugar and salts)
- maintains internal pressure to support cell
function of chloroplasts
- where photosynthesis occurs
- contains chlorophyll
function of chromosomal DNA
- controls cells activity and replication
- floats free in cytoplasm
function of plasmid DNA
- small loops of extra DNA
- contain genes for drug resistance
- can be passed between bacteria
function of flagellum
- hairlike structure rotates to make bacterium move
- used to move away from toxins
- used to move towards nutrients and oxygen
what is a specialised cell
cells with a structure that is adapted to their specific function
examples of specialised cells
- sperm cell
- egg cell
- ciliated epithelial cell
how is an egg cell adapted to its function
- nutrients in cytoplasm which supplies energy the embryo needs to grow
- haploid nucleus
- membrane (jelly coat) hardens after fertilisation to prevent more sperm getting in
how is an sperm cell adapted to its function (4)
- long tail to swim to egg
- lots of mitocondria in mid section to release energy allowing to swim to egg cell
- acrosome (at front of head) stores enzymes to digest membrane of egg cell
- haplod nucleus
how is an ciliated epithelial cell adapted to its function
- line surfaces of organs and airways
- cilia (hairlike structures) ontop of cell that move substances such as mucus away from lungs
define haploid
contains half amount of genetic info (chromosomes) of an average body cell
define diploid
contains a full set of genetic information
what is a light microscope
- pass light through a specimen
- allow us to see nuclei and chloroplasts
- can be used to study living cells
disadvantage of light microscope
- limited magnification
- limited resolution
what is an electron microscope
- pass electrons through specimen
- see internal structure of mitochondria and chloroplasts
- greater understanding of how cells and subcellular structures work
advantages of electron microscope
- greater magnification
- greater resolution
(than light microscope)
disadvantage of electron microscope
cant be used to observe living cells
what is resolution
how clearly an image appears
total magnification
eyepiece lens x objective lens
magnification
image size/ actual size
units of measure in order from largest to smallest
millimetre
micrometre
nanometre
picometre
millimetre (mm)
- convert to micrometre: x1000
- standard form: x10^-3m
micrometre (μm)
- convert to millimetre: ÷1000
- convert to nanometre: x1000
- standard form: x10^-6m
nanometre (nm)
- convert to micrometre: ÷1000
- convert to picometre: x1000
- standard form: x10^-9m
picometre (pm)
- convert to nanometre: ÷1000
- standard form: x10^-12m
what are enzymes
biological catalysts
what is a catalyst
something that speeds up a chemical reaction w/o being used up
what do chemical reactions involve
substances being split apart and joined together
what is a substrate
the molecule changed in the reaction
what part of an enzyme makes it particular to a substrate
active site
how do substrate and active site join together
lock and key mechanism
effect of temperature on enzyme rate of reaction
- increasing temp increases rate at first
- gets too hot and the enzymes denature substrate wont fit
- enzymes have an optimum temp they work best at
effect of PH on enzyme rate of reaction
- if PH is too high or low, enzyme will denature
- all enzymes have an optimum PH, often neutral (7) but not always
effect of substrate conc on enzyme rate of reaction
- higher substrate conc, faster rate of reaction as it is more likley for enzyme and substrate to meet
- up to a certain point, all active sites are full, adding more makes no diff
what can enzymes do
break down large molecules
build small molecules back up
what enzyme breaks down starch
amylase into maltose
what enzyme breaks down protein
protease into amino acids
what enzyme breaks down fat
lipase into fatty acids and glycerol
diffusion
net movement of particles from an area of high to low concentration (along conc grad)
osmosis
movement of water molecules across a partially permeable membrane along a conc grad
active transport
movement of particles across a membrane against a conc grad using energy from respiration
Describe how the lock and key mechanism works
- enzymes bind to the substrate as they are complimentary
- The substrate is broken down into products
- The products are then released
