key concepts Flashcards
What 3 things define a cell?
- cells are the smallest unit of life
- all living things are made of cells
- all cells come from pre-existing cells
What’s in an animal cell? Functions?
Nucleus - stores dna, controls cell
Cell membrane - controls substances that enter and leave cell
Mitochondria - aerobic respiration occurs, produces energy for cell
Ribosomes - protein synthesis
Cytoplasm - chemical reactions occur
What’s in a plant cell? Functions?
Nucleus
Cell Membrane
Mitochondria
Ribosomes
Cytoplasm
Cell wall - provide structure & protection
Chloroplasts - photosynthesis making glucose for plant
What’s in a bacterial cell? Functions?
Cell membrane
Ribosomes
Cytoplasm
Chromosomal dna - holds all genes & dna needed for cell
Plasmid dna - contain additional genes
Flagella - to move the bacterium
What does a sperm cell have? Functions?
Midpiece - contains mitochondria to release energy to swim
Haploid nucleus - contains genetic material for fertilisation
Acrosome - contains enzymes so that it can penetrate an egg
Tail - swim
What’s in an egg cell? Functions?
Mitochondria
Cell membrane
Haploid nucleus
Cytoplasm - contains nutrients for growth of embryo
What is the purpose of cilia?
Move fluids & particles up the trachea.
What are the 2 types of microscopes? Functions?
Light - study living cells & when low magnification & resolution is enough
Electron - smaller specimen & when high magnification & resolution is needed
What’s the formula for magnification of microscope?
magnification of eyepiece x magnification of objective
What’s the formula for magnification of an image?
real size of object x magnification
How do u get from…
cm - m m - cm
mm - m m - mm
mm - cm cm - mm
µm - mm mm - µm
nm - µm µm - nm
/100 x100
/1000 x1000
/10 x10
/1000 x1000
/1000 x1000
Parts of a light microscope & function?
Eyepiece - look through
Barrel - to focus image
Turret - moved up or down to change magnification lens
Lens - rotated to increase magnification
Stage - flat surface with specimen
What’s the method for preparing a side?
- peel or slice a thin layer
- add a drop of water
- add a small amount of a chemical stain to make cells more visible
- gently put the layer on a glass slide
- carefully put a coverslip on the slide, avoiding air bubbles
What are enzymes?
Proteins that function as biological catalysts, speeding up chemical reactions without being changed.
Explain enzymes colliding with a substrate.
- substrate collides with active site and becomes attached (complimentary shape)
- enzyme catalyses breakdown of substrate (fit is like lock & key)
- products released from active site (enzyme unchanged, can be reused)
Enzymes denature when…
They’re exposed to extremes of pH or temperatures
What happens when an enzyme denatures?
The substrate will no longer fit into the enzyme.
What’s the effect of ph and temp on enzymes?
As the ph or temp is increased above or decreased below the optimum, enzyme activity decreases.
What’s the effect of substrate concentration on enzymes?
Rate of enzyme activity increased with substrate concentration but it doesn’t increase forever.
What is diffusion?
Movement of molecules from a region of higher to lower concentration.
Diffusion has a ____ permeable membrane meaning…
Semi
It allows some molecules to cross easily but others with difficulty or not at all.
Diffusion helps living organisms to…
Get rid of waste products
Carry out gas exchange for respiration
What is osmosis?
Movement of water molecules from a region of higher (dilute) to lower water potential (concentrated).
Diffusion & osmosis are forms of ______ _______ meaning…
Passive transport
It doesn’t require energy
