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42 Cards in this Set
- Front
- Back
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what are centrioles?
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-a hollow cylinder
-formed from a ring of microtubules -grow spindles for/during nuclear division (mitosis) |
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what is the nucleus?
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-the largest cell organelle
-contains genetic material that controls the cells activities -surrounded by the nuclear envelope -contains the nucleolus -chromatin are found here. |
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what is the nucleolus?
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-found inside the nucleus and manufactures ribosomes and RNA
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what do chromatin consist of?
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DNA and proteins
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what is the nuclear envelope?
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-made of 2 membranes with fluid inbetween them
-has nuclear pores allowing exchange between the cytoplasm and the nucleus -outer membrane is continuous with the endoplasmic reticulum |
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endoplasmic reticulum
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-2 types: rough ER and smooth ER
-made of flattened membrane bound sacs called the cisternae. +smooth -involved in the making of lipids that the cell needs +rough -studded with ribosomes -transports proteins on the ribosomes -some will be secreted from the cell -others will be placed on the surface of the membrane |
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golgi apparatus
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-made of membrane bound flattened sacs
-recieves proteins from ER and modifies them (adding or taking away sugars) -packages proteins into vesciles so they can be transported -some will go to the surface so they can be secreted |
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mitochrondria
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-looks spherical or sausage shaped
-two membranes seperated by fluid filled spaces -inner membrane is called the cristae and is folded -central part of mitochrodria is called the matrix. -the site where ATP is produced during respiration |
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chloroplasts
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-only found in PLANT cells
-2 membranes seperated by fluid filled sacs -inner membrane is continuous -made of flattened sacs called thylakoids -a stack of thylakoids is called a granum -chlorophyll found in the thylakoid membranes and the integranal membranes -the site for photosynthesis |
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what are carbohydrate molecules made from?
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carbon dioxide and water
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lysosomes
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-spherical sacs surrounded by a single membrane
-contain digestive enzymes -role is to break down materials |
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ribosomes
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-very tiny
-sites for protein synthesis -found in the cytoplasm or the rough ER -mRNA from the nucleus is used to assemble proteins from amino acids |
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cilia
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-thin cell extensions
-contain microtubules -move in a synchronised pattern moving substances surrounding the cell or the cell itself |
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how do you find the actaul size of a diagram?
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- A measure the diagram in mm
- B measure the bar at the bottom in mm -divide A by B A ---- B - C times by the number on the bar (if in um) - A ---- x C = lenght in um B -to get this in mm you divide by 1000 -if C is in mm, convert it to um by x 1000 or x1000 at the end |
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convert 0.25um into mm
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0.25
----- =0.00025mm 1000 |
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convert 200nm into mm
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200
--------- = 0.0002 100 000 |
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convert 0.3mm into um
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0.3 x 1000 =300um
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who created the cell threory?
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robert hooke 1665
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what was the cell theory?
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-all living things consist of cells
-new cells are only made by pre-existing cells -cells contains instruction that act as inforamtion for growth |
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cytology
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study of the cell
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magnification
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degree to which the image is larger than the object itself
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resolution
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degree to which you can distinguish between two objects that are very close together
higher the resolution the greater detail |
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how do you find the magnification?
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-find the epu to 1 mm
-measure the image/cell -divide the cell by the epu -x1000 to get um |
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mm and um
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x1000 to get um
divide by 1000 to get mm |
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division of labour
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-found in animal and plant cells
-each type of orgsnelle has a specific job -all work as a team -known as division of labour |
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cytoskeleton
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-the network of protein fibres found within a cell
-gives the structure and the shape -moves the organelles around inside the cells |
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LM
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light microscope
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EM
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elctron microscope
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describe how the LM works and preperations needed
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-some need to be stained
-acetic orcein stains DNA dark red -specimens embedded in wax -sections are then cut without distorting the specimen -then put onto glass slide -put on stage -condensor focusses light from the illuminator to the specimen -objective lens controls the magnification and resolution -light processes through the specimen to the eyepiece |
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how do you work out the total magnification from the LM?
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objective magnification xeyepiece magnification
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how does the EM work?
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-cathode emits the high velocity electron beam
-annode accelerates the electron beam -condensor foccuses the electron beam onto the specimen -objective lens magnifies and foccuses the first image -projector gives further magnification selecting region to be viewed -electrons bounce of specimen in SEM -air lock allows the specimen into the EM without loss of vacum -can be viewed directly by screen being coated with electron sensitive compounds -vacum pump minimises electrons scattering and any heat collisions |
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what are the advantages of both EM and LM
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+LM
-cheaper -not so much preperation required +EM -used to produce detailed images -SEM produces 3D images that give detail |
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what are the disadvantages of EM and LM?
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+LM
-doesnt give detail -often blurred and innacurate -only magnifies up to x1500 +EM -must be places in a vacum -very expensive |
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what are the similarities of EM and LM?
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+similarities
-magnify cells -both have an eyepiece -both njeed to be prepared +differences -LM=can only be seen as 2 objects when 200nm apart -EM=can be seen as 2 objects when 0.2nm apart -EM has better resolution |
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TEM
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-transmission electron microscope
-electron beam passes through sample -image is 2D -magnification up to x500 000 |
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SEM
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-scanning electron microscope
-electron beam bounces off sample -image produced is 3D -magnification up to x100 000 |
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what is a prokaryotic cell?
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-cells without a true nucleus
-for example bacteria and amoeba |
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what are the properties of a prokarytoic cell?
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-genetic material is in the cytoplasm or the plasmid
-DNA is ALWAYS attached to the cell membrane -do NOT have mitochrondria, chloroplasts or ER -DO have ribososmes that are smaller and always free in the cytoplasm (20nm diameter) -surrounded by a cell wall that is made up of fibres of peptidoglycan. this stops the cell bursting if/when it expands -have no cytoskeleton -no histones on/with the chromosomes -some will have flagella but with a different structure -ATP production occurs in the mesosomes |
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what are the properties of a eukaryotic cell?
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-nucleus present
-linear chromosomes -ribosomes 30nm in diameter and attached to the ER -cell wall made of cellulose -mitochrondria ususally present -DNA associated with histones and found in the nucleolus -ER always present cell membrane around the cell itself and also the organelles inside the cell. e.g mitochrondria |
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prokaryotes that cause disease
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-some prokaryotes are bacteria
-they can become resistant to antibiotics like MRSA -resistance is coded on the plasmid DNA -they share and swop plasmids with each other so therefore can pass the resistance on -resistance can also be passed on to the daughter cells by binary fission |
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prokaryotes that help
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-food industry uses prokaryotes like cheese and yoghurts
-bacterial cells in the body help with the digestion and vitamin K production -skin is covered with the "normal flora" of bacteria as this helps prevent harmful microorganisms from getting into the body -sewage treatments also rely on the bacterial cells that help digest and respire dead and animal waste material |
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describe the production and excretion of protein in the cells
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-DNA in the nucleus carries instructions to produce the protein
-each gene has the instruction for 1 protein -DNA is used to produce a molecule called mRNA that will carry the instructions out of the nucleus -mRNA molecule leaves the nucleus via a nucleatr pore in the nuclear envelope -ribososmes produce protein molecules using instructions carried on the mRNA -after the ribososmes produce the protein molecule they are pinched off into vesciles and moved to the golgi apparatus -the golgi apparatus packages and processes the proteins. -proteins such as insulin are made in this way, along with the growth hormones |
