Topic 2A: Cell structure and division

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What are organelles?
They're parts of cells that have a specific function
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What organisms are eukaryotic?
Animals, plants, algi and fungi
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What extra parts do plant cells have that animal cells do not?
Plant cells have a cellulose cell wall, a vacuole and chloroplasts
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Are starch grains organelles?
NO
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What is the difference (in terms of chloroplasts) of algal and plant cells?
Algal cells have chloroplasts in a different shape and size for example, they may just have one big chloroplast instead of several smaller ones (like a plant cell)
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What's the difference between fungal and plant cells?
Fungal cells' cell wall is made of chitin, not cellulose and they don't have chloroplasts
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What is the function of the cell-surface membrane?
They regulare the movement of substances in and out of the cell. They also have receptor molecules to allow the cell respond to hormones
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What is the cell-surface membrane made from?
Mainly lipids and proteins
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What is the function of the nucleus?
It controls the cell's activities by controlling the transcription of DNA
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What does the nucleolus make?
Ribosomes
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What is the function of the mitochondria?
It is the site of aerobic respiration and it produces ATP
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Name the 4 parts of mitochondria
Matrix, crista, inner/outer membrane
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What is the function of the chloroplasts?
They're the site of photosynthesis
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What are grana linked together by?
Lamellae
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What is the stroma?
It is a thick liquid found in the chloroplasts
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What is the function of the golgi apparatus?
They process and package new lipids and proteins and make lysosomes
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What is the golgi apparatus?
They're a group of fluid-filled membrane bound sacs
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What is the function of the golgi vesicle?
They store lipids and proteins made by the apparatus and transports them out of the cell
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What is the function of lysosomes?
They contain digestive enzymes called lysozymes that can digest invading cells or break down worn out components of the cell
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What is the function of ribosomes?
Where proteins are made (translation)
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Where can you find a ribosome in the cell?
Free floating in the cytoplasm or attatched to the rough endoplasmic reticulum
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What is the function of the rough endoplasmic reticulum?
It folds and processes proteins that have been made at the ribosomes
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What is the function of the smooth endoplasmic reticulum?
They synthesise and process lipids
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What's different about the structure of the RER compared to SER?
RER is covered in ribosomes, SER is not
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What's the function of the cell wall?
Supports the cell and prevents it from changing shape
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In what cells is a cell wall found?
Plant, algae and fungi cells
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What is a tonoplast?
The surrounding membrane of the cell vacuole
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What is the function of the cell vacuole?
To maintain pressure inside the cell and keep it rigid - this stops the plant wilting. It also isolates the unwanted chemicals inside the cell
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What is the cell sap made of?
It is a weak solution of sugar and salts
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How are sperm cells adapted to their function?
They contain a lot of mitochondria to provide a lot of energy as they swim 2 the egg
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How are red blood cells adapted to their function?
They have no nucleus to make room for haemoglobin
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How are epithelial cells adapted to their function?
Microvilli & villi to increase surface area, they have lots of mitochondria for active transport
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What is an organ?
Different tissues that work together to perform a particular function
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What are tissues?
A collection of specialised cells that are grouped together that work together to perform a particular function
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Are ribosomes bigger or smaller in a prokaryotic cell compared to a eukaryotic cell?
They're smaller in a prokaryotic cell
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What is a cell wall made out of in a prokaryotic cell?
Murein (a glycoprotein)
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What is the point of having a capsule made of secreted slime?
It helps protect bacteria from the attack by cells of the immune system
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What does a prokaryotic cell have instead of a nucelus?
It has free floating DNA which is circuar and one long coiled up strand. Also has plasmids
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What is the function of a flagellum?
It helps the cell move
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What do the genes in plasmids contain?
The genes contain things like antibiotic resistance
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How big are prokaryotic cells?
2 micrometres in diameter (0.002mm)
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What's bigger: eukaryotic or prokaryotic cells?
Eukaryotic cells: 0.1mm compared to 0.002mm
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What is the process by which prokaryotic cells replicate
Binary fission
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What happens during binary fission?
The prokaryotic cell replicates its genetic material before physically splitting into two daughter cells
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What are host cells?
The cells that viruses invade and reproduce inside of
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What are the 3 parts of a virus?
Core of genetic material, capsid and attatchment proteins
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What is a capsid?
A protein coat with attatchment proteins sticking out of it
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What do attatchment proteins cling on to?
The suitable host cell's complementary receptor proteins on the cell membrane
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Do viruses have DNA or RNA?
They can have either
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What is magnification?
How much bigger he image is than the specimen
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How is magnification calculated?
Magnification = size of image / size of real object
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Order these from smallest to biggest: um nm mm
nm um mm
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What is resolution?
How detailed the image is - how well a microscope distinguishes between two points that are close together
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How do you convert mm into um?
x1000
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What are the two types of microscopes?
Optical and electron
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What are the two types of electron microscope?
Transmission and scanning
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How does a TEM work?
They use electromagnets to focus a beam of electrons which is then transmitted through the specimen - denser parts absorb more electrons which makes it look darker
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How does a SEM work?
SEMs scan a beam of electrons across the specimen which knocks off electrons from it which are then gathered in a cathode ray tube to form an image
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What's an advantage of TEMs?
They give high resolution images, so show small objects
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What are the disadvantages of TEMs?
They can only be used on thin and non living specimens
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What are the advantages of SEMs?
They can be used on thick specimens & can be 3D
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What are the disadvantages of SEMs?
They give lower resolution images than TEMs and can only be used on non living specimens
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Why are TEMs not good for looking at living organisms?
They have to be viewed in a vacuum
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Is the magnification higher in a optical or electron microscope?
Electron (1 x 500,000) (vs optical: 1 x 1,500)
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Is the resolution higher in a optical or electron microscope?
Electron (max of 0.0002um) (vs optical max of 0.2um)
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Why are stains used?
They're used to highlight objects in a cell
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What are microscope artefacts?
They are things you can see down the microscope that aren't part of the cell or specimen you're looking at (e.g. air bubbles or dust)
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What are some examples of microscope artefacts?
Air bubbles, fingerprints, dust
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Why do microscope artefacts appear?
Due to inaccuracies caused by squashing and staining the sample
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What's the process that seperates organelles in a cell?
Cell fractionation
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What are the three steps to cell fractionation?
1. Homogenisation 2. Filtration 3. Ultracentrifugation
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Give two says homogenisation can be done
Vibrating the cells or grinding them in a blender
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Why should the solution be isotonic during homogenisation?
To prevent damage to the organelles through osmosis
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What does isotonic mean?
The same concentration of chemicals as the cells in the solution (or something idk)
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Why is a buffer solution added during homogenisation?
To maintain pH
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In what order are the organelles seperated during ultracentrifugation?
Nuclei, Chloroplasts, Mitochondria, Lysosomes, ER, Ribosomes
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What is a centrifuge?
A machine that seperates material by spinning
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Where are the heavier organelles found during ultracentrifugation?
In the pellet
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What are the 3 stages of interphase?
G1, synthesis and G2
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What happens during G1?
Cells grow new organelles and proteins are made
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What happens during synthesis?
The cell replicates its DNA, ready to divide by mitosis
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What happens during G2?
The cell keeps growing and proteins needed for cell division are made
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BRIEFLY describe what happens during mitosis
A parent cell divides to produce two genetically identical daughter cells
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What are the 5 stages of mitosis?
Interphase, prophase, metaphase, anaphase, telophase (IPMAT init)
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What is a centromere?
What joins two chromosomes in the middle
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What is a chromatid?
One arm of a double stranded chromosome
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What happens during prophase?
Chromosomes condense, centrioles move to opposite ends of the cell, the nuclear envelope breaks down and chromosomes lie free in the cytoplasm
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What happens during metaphase?
The chromosomes line up along the middle of the cell and become attatched to the spindle by their centromere
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What happens during anaphase?
The centromeres divide and spindles contract, pulling chromatids to opposite poles of the spindle.
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What happens during telophase?
The chromatids reach opposite poles on the spindle and they uncoil to just be chromosomes again. A nuclear envelope forms and cytokenisis happens
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What is cytokenisis?
Bascially when the cytoplasm divides
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What is cancer?
It is a tumour that invades surrounding tissue
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What causes cancer?
A mutation in a gene that controls cell division, so cells divide uncontrollably
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How do you calculate mitotic index?
Mitotic index = number of cells with visible chromosomes / total number of cells observed
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Card 2

Front

What organisms are eukaryotic?

Back

Animals, plants, algi and fungi

Card 3

Front

What extra parts do plant cells have that animal cells do not?

Back

Preview of the front of card 3

Card 4

Front

Are starch grains organelles?

Back

Preview of the front of card 4

Card 5

Front

What is the difference (in terms of chloroplasts) of algal and plant cells?

Back

Preview of the front of card 5
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Workangel_24

Great flash cards!!!

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