Cells Flashcards
What are Cells
The building blocks of life, all living things are made out of cells
What are groups of cells called
Tissue
What are groups of tissue called
An organ
unicellular
organisms made up of only one cell
multi-cellular
organisms made up of multiple cell
what is the mnemonic for the seven life processes that are need for an organism to stay alive
MRS GREN
What does MRS GREN stand for
Movement - The organism can change its position
Respiration - The organism releases energy from a ‘food’ source, this requires oxygen
Sensitivity - The organism responds to things
Growth - The organism gets bigger
Reproduction - The organism makes copies of themselves
Excretion - The organism gets rid of waste material
Nutrition - The organism consumes chemical
material as food
Eukaryotic Cell
Can be both Unicellular and Multi-Cellular
A type of cell with a nucleus containing DNA and other membrane-bound organelles is called a eukaryotic cell
Size - 2-200μm
(e.g. Animal Cell, Plant Cell or Fungi Cell)
Prokaryotic Cell
Can only be Unicellular
Are much smaller than eukaryotic cells (Less than 2μm)
No membrane-bound organelles
Have a cell wall – but it isn’t made of cellulose like a plant cell wall (made of peptidoglycan)
Doesn’t have a nucleus
Can’t store genetic material in a nucleus (it is a single DNA loop)
May have one or more small rings of DNA called plasmids
(e.g. Bacteria Cells)
What sub-cellular structures (organelles) do animal cells contain
a nucleus cyctoplasm a cell membrane mitochondria ribosomes
What sub-cellular structures (organelles) do plant cells contain
a nucleus cyctoplasm a cell membrane mitochondria ribosomes chloroplasts a permanent vacuole filled with cell sap cell wall
Function of Nucleus
Controls the activities of the cell
Contains DNA
Function of Cell Membrane
Controls what passes in & out of a cell
Function of Cell Membrane
Holds the cell together
Controls what passes in & out of a cell
Function of Ribosome
Site of protein synthesis (where proteins are made)
Function of Cell Wall
Gives the cell a rigid strong structure
Made of cellulose
Keeps shape of cell box-like
Function of Vacuole
Contains sap
Helps support the shape of the cell
Function of Chloroplast
Contains Chlorophyll (needed for photosynthesis) (green in colour)
Function of Vacuole
Contains Cell Sap
Helps support the shape of the cell
Function of Cell Sap
Stores materials such as sugars, amino acids, waste substances (such as tannins), and mineral salts
How to draw a diagram of an animal cell
Oval like structure for Cell Membrane
In centre of Oval is the One Nucleus which is a circle
Cytoplasm is around it
Ribosomes are dots scattered around
Mitochondria are fewer than Ribosomes and look like a baguette
How to draw a diagram of a plant cell
Rectangular box-like structure for Cell Membrane
A slightly bigger rectangle around Cell Membrane for Cell Wall
In centre of Box is the Vacuole which is big and covers most of the space - quite box like as well
Cytoplasm is around it
The One Nucleus is a circle in the cytoplasm area
Ribosomes are dots scattered around
Mitochondria are fewer than Ribosomes and look like a baguette
Chloroplasts are Ovals slightly bigger than Mitochondria but have no baguette design (sometimes green)
How big is an animal cell usually
1/100mm
How big is a plant cell usually
40 times as big as an animal cell
What sub-cellular structures (organelles) do bacteria cells contain
cytoplasm cell membrane cell wall ribosomes flagella circular DNA capsule plasmid Pili
Function of Capsule (most bacteria)
Protection from damage
For sticking prokaryotic cells together
Slimy or Gelatine-like
Function of Flagella/Flagellum (some bacteria)
Movement
A long protein strand that lashes about helping them to move
Function of Pili (some bacteria)
For movement
For sticking to surfaces
(e.g. bacteria may stick to body cells to begin causing disease)
Function of Plasmid (some bacteria)
Extra bits of circular DNA, genes in the plasmids can be for antibiotic resistance
Some produce toxins
How to draw a diagram of a bacteria cell
Cell Membrane is a capsule / oval structure
Cell wall is a slightly bigger oval structure surrounding the Cell Membrane
Capsule is a slightly bigger oval structure surrounding the Cell Wall
Genetic material is free and not contained in a nucleus. The bacterial chromosome or long strand of DNA is usually circular. Draw it as a line in the middle of the oval weaving in and out of itself the connecting back up to the start in the end
Plasmids are also like this strand but are separate and are circular looking
Pili are strands coming out in all directions outwards from the capsule (look like legs of a centipede)
Ribosomes are dots scattered around
Flagella is a tail coming out from the shorter end of the bacteria cell usually the right hand side
Similarities between Eukaryotes and Prokaryotes
A plasma membrane
Cytoplasm
Ribosomes for protein synthesis
DNA and RNA
Why Prokaryotes are different from Eukaryotes
They have no nucleus
They have linear chromosomes
They have no membrane bound organelles
They have larger ribosomes
Their cell wall is made of peptidoglycan and not cellulose or chitin (fungi cells walls)
Have a less well developed cytoplasm with no centrioles (centrioles are involved in cell division which will be covered later)
(Some bacterial cells also have a slime/waxy capsule, plasmids, flagella and pili)
Pre 1970 what system of classification was used
Five Kingdoms
Monera - Prokaryotes (Bacteria + Archaea)
Prostita - Anything else (e.g. Amoeba + Algae)
Plantae - Plants
Fungi - Fungi
Animalia - Animals
They were classified on observable traits
What are Archaea
Small, single-celled organisms that live in extreme environments (extremophiles)
Size and structure of Archaea ribosomes are the same as bacteria BUT the nucleic acids in the ribosomes are more similar to Eukaryotes
Also Cell Wall didn’t contain peptidoglycan which Bacteria did but did have other materials in cell wall that bacteria did have (Proteins, Lipids, and Polysaccharides)
In 1977 Carl Woese decided if these organisms lived in these extreme environments, they must be something different
Post 1970 what system of classification was used
Three Domains
Bacteria - all types of bacteria
Archaea - all types of archaea
Eukarya - all Eukaryotes including Plants, Animals, Fungi, Protists and more
Structure of a Light Microscope (14 parts)
From top to bottom
eyepiece lens body tube arm revolving nosepiece low power objective lens medium powered objective lens high powered objective lens stage clip stage diaphragm fine focusing knob coarse focusing knob light source base
What is magnification
The ability of a lens or other optical instrument to magnify (enlarge) the size of something in an optical image.
How is the magnified image produced
Two lenses, an eyepiece lens (fixed) and an objective lens (can choose).
How do you find the total magnification
Magnification of Eye Piece Lens (fixed to x10) * Magnification of Objective Lens
What is resolution
Ability of a microscope to distinguish two adjacent points as separate from one another.
Maximum resolution is the smallest distance between two points, at which they may be recognised as two separate entities.
The better the resolution, the better you are able to view and identify finer details.
What is need in a Scientific Drawing
No shading. Areas that should be shaded should be labelled instead.
Clear, continuous lines
The drawing should take up at least half of the page.
Label lines must be completely horizontal, drawn with a ruler, exactly touch the object that they’re labelling and must not overlap each other.
Drawing lines should completely connect.
They should be drawn in a sharp pencil and look like the actual image.
Include a title
Include a scale if relevant
Also include total magnification if you are drawing a diagram of something under a microscope
Labels should be off the diagram
Include annotation - colour, function, adaption for example
What are the two types of microscopes
Light Microscope
Electron Microscope
Advantages of a Light Microscope
Cheaper Can see specimens in colour Can use Living/Dead specimens Mobile / Portable Can see outside of the cells and nucleus
Disadvantages of a Light Microscope
Lower Magnification than Electron Microscope (x2,000)
Lower Resolution than Electron Microscope (around 200nm)
Advantages of an Electron Microscope
Higher Magnification than Light Microscope (up to x2,000,000)
Higher Resolution than Light Microscope (around 0.1nm)
No complex lighting system needed
Can see inside of the cell
Disadvantages of an Electron Microscope
Costs approx. £1M Expert preparation Affected by magnetic fields Maintenance Cost Dead Specimen only Difficult to create sample Fixed / Large No colour (only B&W)
What are the two types of electron microscope and how are they different
SEM - Scanning Electron Microscope - Scans surface of a sample
TEM - Transmission Electron Microscope - Electrons penetrate the sample
Size of various objects
The smallest thing we can see is about 0.04mm
Most cells are so small so we used the unit micrometre (μm)
Viruses and organelles are even smaller – so we can use the unit nanometre (nm)
Centimetre (cm) to Millimetre (mm)
x10
Millimetre (mm) to Micrometre (µm)
x1,000
Micrometre (µm) to Nanometre (nm)
x1,000
How do you calculate Magnification
Size of Image / Size of Actual Object
Remember this as the I AM triangle
I is on the top while AM is on the bottom.
(This is like the Speed, Distance, Time Triangle or Density, Mass, Volume Triangle)
What is Standard Form and why is it used
A * 10^n (1≤A<10) and (n has to be an integer)
Some numbers may be too big or too small to read or even understand. Writing numbers in standard form makes them easier to comprehend and compare. Also, a calculator may not be able to handle all the numbers in a very large calculation, but by using standard form it can handle numbers of any size.
Standard Form Equivalent of a Millimetre (mm) in Metres (m)
10^-3
Standard Form Equivalent of a Micrometre (µm) in Metres (m)
10^-6
Standard Form Equivalent of a Nanometre (nm) in Metres (m)
10^-9
What is Order of Magnitude
The difference in size in factors of 10
(e.g. if order of magnitude = 1, something is 10x bigger
If order of magnitude = 3, something is 1000x bigger (10x10x10)
How to calculate Order of Magnitude
Convert to same unit Convert that to Standard Form Subtract the smaller value from the bigger value (e.g. 1µm = 0.000001 = 1x10^-6m 100nm = 0.0000001 = 1x10^-7m Order of Magnitude = 1 (-6 - -7 = 1)
