Cell structure and Division Flashcards by Lauren Blake

What is the structure and function of the cell-surface membrane?

-Mainly made of proteins and lipids
-Regulates the movement of substances in and out of the cell
-Has receptor molecules on it

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What is the structure and function of the nucleus?

-Nuclear envelope with pores
-Contains chromosomes
-Contains a nucleolus
-Controls the cells activity
-DNA contains instructions to make proteins
-Pores allow substances to move between the nucleus and the cytoplasm
-Makes ribosomes

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What is the structure and function of the mitochondria?

-Double membrane
-Inner membrane folded to make the cristae
-Inside is the matrix
-Site of aerobic respiration->produces ATP

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What is the structure and function of the chloroplast?

-Double membrane
-Contains thylakoid membranes
-Grana is stacked thylakoid membranes
-Grana are linked together by lamellae
-Site of photosynthesis

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What is the structure and function of the Golgi apparatus?

-Fluid-filled membrane bound flattened sacs
-Vesicles on edge of sacs
-Processes and packages new lipids and proteins
-Makes lysosomes

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What is the structure and function of the Golgi vesicles?

-Fluid-filled sac in the cytoplasm
-Surrounded by a membrane
-Stores lipids and proteins and transports them out of the cell

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What is the structure and function of lysosomes?

-Type of Golgi vesicle
-Round organelle with a membrane and no clear internal structure
-Contains lysozymes

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What is the structure and function of ribosomes?

-Either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum
-Made of proteins and RNA
-Where proteins are made

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What is the structure and function of the rough endoplasmic reticulum?

-System of membranes enclosing a fluid-filled space
-Surface covered in proteins
-Folds and processes proteins made at ribosomes

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What is the structure and function of the smooth endoplasmic reticulum?

-Same as rough but with no ribosomes
-Synthesises and processes lipids

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What is the structure and function of the cell wall?

-In plants, algae and fungi
-In plants->cellulose
-In fungi->chitin
-Supports cells and prevents them from changing shape

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What is the structure and function of the cell vacuole?

-Contains cell sap
-Surrounding membrane->tonoplast
-Maintains pressure inside cell and keeps the cell rigid.

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What are the adaptations of the epithelial cells in the small intestine?

-Villi which increase the surface area
-Microvilli which further increase the surface area
-Lots of mitochondria

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Name an adaptation of red blood cells.

-No nucleus to allow them to carry more oxygen

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Name an adaptation of sperm cells.

-Lots of mitochondria for energy

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Name the organelles present in a prokaryotic cell.

-Cytoplasm contains ribosomes (ribosomes are smaller than in a eukaryote)
-Cell-surface membrane (same as eukaryotic)
-Cell wall, made of murein (a glycoprotein)
-Capsule
-Plasmids (small loops of DNA)
-Circular DNA (not attached to histone proteins)
-Flagellum

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Describe the process of binary fission.

-Circular DNA and plasmids replicate, circular DNA only replicated once but plasmids can be replicated multiple times
-Cells gets bigger and the DNA loops move to opposite poles of the cell
-Cytoplasm begins to divide and new cell wall begins to form
-Cytoplasm divides and two daughter cells are produced

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Name 3 differences between a virus and a eukaryotic cell.

-Viruses are acellular and eukaryotic cells are cellular
-Viruses contain attachment proteins
-Viruses have a capsid

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Describe the steps of viral replication

-Virus attaches to hist cell receptor proteins
-Genetic material released into host cell
-Genetic material and proteins are replicated by host cell
-Viral components assemble
-Replicated viruses are released from the host cell

What is the equation linking magnification, image size and real size?

magnification=image size/real size

How do you convert millimetres to micrometres?

x1000

How do you convert micrometres into nanometres?

x1000

Define resolution

How well a microscope distinguishes between two points that are close together

What organelles cannot be viewed under a optical light microscope?

-Organelles smaller than 0.2 micrometres
-e.g. ribosomes, endoplasmic reticulum and lysosomes

Why are electron microscopes better to use when viewing organelles?

-they have a higher magnification and resolution

What are the advantages of a transmission electron microscope (TEM)?

-High resolution images so shows small images

What are the disadvantages of a transmission electron microscope?

-Can only be used on thin specimens -Can only be used on non-living specimens

What are the advantages of a scanning electron microscope (SEM)?

-Can be used on thick specimens -Can be 3-D

What are the disadvantages of a scanning electron microscope?

-Lower resolution images than a TEM -Can only be used on non-living specimens

How do you prepare a microscope slide?

-Pipette a small amount of water onto the centre of the slide -Use tweezers to place a thin specimen on the water drop -Add a drop of stain -Add the cover slip, make sure there are no air bubbles

What are the three steps of cell fractionation?

-Homogenisation Filtration -Ultracentrifugation

Describe the process of homogenisation

-Cells broken up in a blender and organelles released into a solution -Solution should be ice-cold to reduce enzyme activity, isotonic to prevent osmotic activity and buffered to maintain the pH

Describe the process of filtration

-Solution filtered through a gauze to separate large cell debris or tissue debris from organelles

Describe the process of ultracentrifugation

-Cell fragments are poured into a tube, which is put in the centrifuge and spun at a low speed. -Heaviest organelles are pushed to the bottom of the tube and form a pellet, the rest of the organelles stay suspended in the supernatent. -Supernatent is drained off and poured into another tube and spun again, but at a higher speed -Process repeated, with speed increasing each time.

What is the order of the heaviest organelles?

-Nuclei -Chloroplasts (in plants) -Mitochondria -Lysosomes -Endoplasmic reticulum -Ribosomes

What are the stages of the cell cycle?

-M->Mitosis -G1->Gap phase, cell grows and new organelles and proteins are made -S->Synthesis, cell replicates its DNA -G2->Gap phase 2, cell keeps growing and proteins needed for cell division are made

What stages of the cell cycle occur during interphase?

-G1,S and G2

What are the stages of mitosis?

-1->Interphase -2->Prophase -3->Metaphase -4->Anaphase -5->Telophase

What happens during the interphase?

-DNA is unravelled and replicated -Organelles are replicated -ATP content is increased

What happens during prophase?

-Chromosomes condense (get shorter and fatter) -Centrioles start moving to opposite ends of the cell -Nuclear envelope breaks down

What happens during metaphase?

-Chromosomes line up along the middle of the cell -Attach centrioles to centromeres by spindle fibres

What happens during anaphase?

-Centromeres divide -Separating each pair of sister chromatids -Spindle fibres contract, pulling chromatids to opposite poles of the cell -Chromatids appear v-shaped

What happens during telophase?

-Chromatids uncoil and become long and thin (now chromosomes) -Nuclear envelope forms around each group of chromosomes -Cytoplasm divides (cytokinesis) -Two genetically identical daughter cells are made

How would you prepare a root tip cell squash?

-Add some 1M HCl to a boiling tube, put the tube in a water bath at 60degrees -Use a scalpel to cut 1cm from the tip of a growing root -Transfer the root tip into the boiling tube, incubate for 5 minutes -Use tweezers to remove the root tip from the tube and rinse it with cold water -Place root tip on the microscope slide and cut 2mm from the tip of it -Use a mounted needle to break the tip open and spread the cells out thinly -Add few drops of stain -Place a cover slip over the cells and put a piece of folded filter paper on top, squash the the tissue

How do you calculate the mitotic index?

mitotic index=number of cells with visible chromosomes/total number of cells

How do you calculate the actual size of cells?

actual size=size of image/magnification