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Biology Unit 1- 12th May > 1.2 Cell Ultrastructure > Flashcards

1.2 Cell Ultrastructure Flashcards

1
Q

Who created the microscope?

A

-Robert Hooke
-1665

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2
Q

Who devised the cell theory and what is it?

A

-Schleiden and Schwann in 1839
-All living organisms are made of one or more cells.
-The cell is the most basic unit of life
-Cells can only arise from pre- existing cells

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3
Q

2 types of microscopes

A

-Light microscope
-Electron microscope

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4
Q

Light microscope

A

-x1,500 magnification
-200nm resolving power
-Eyepiece lens magnification x Objective lens magnification = Total magnification
-Common stains = Haematoxylin+ Eosin stain, Methylene Blue, Iodine

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5
Q

Pros + Cons of light microscopes

A

Pros= Cheap, accessible and portable
-Can look at live cells with little preparation e.g blood samples and sperm

Cons= Limited in terms of magnification and resolution

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6
Q

Electron microscope

A

-x500,000 magnification
-0.5nm resolving power
-Beam of electrons rather than a beam of light
-Smaller wavelength
-2 types = Transmission electron microscope (TEM) + Scanning electron microscope (SEM)
-TEM = images produced are black + white + 2D but SEM produces 3D images and colour can be added after

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7
Q

Pros + Cons of electron microscope

A

Pros= massive magnification and massive resolution

Cons= have to examine specimens in a vacuum so they have to be dead and dried of all water
-very expensive
-large
-very specialised skills required to prepare samples
-artefacts likely

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8
Q

Cutting plane

A

-Determine what you see on the slide

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9
Q

Cells can be split into 2 categories

A

1- Prokaryotic cells
2- Eukaryotic cells

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10
Q

Viruses

A

-Do not have cell organelles found in cells
-Made of a protein coat called a CAPSID on the outside and has some DNA or RNA inside
-Not living
-No nucleus
-No metabolism
-Must reproduce inside a living host cell

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11
Q

Nucleus

A

-largest organelle
-double membrane called the nuclear envelope
-nuclear pores allow ribosomes to travel through
-nucleoplasm contains DNA in the form of chromatin when not dividing and chromosomes when it it
-contains the nucleolus

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12
Q

Nucleolus

A

-dense darker area of the nucleus
-produces ribosomes and RNA

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13
Q

Ribosomes

A

-made of ribosomal RNA and protein
-made in nucleus then moved through the cell
-used in protein synthesis to assemble the polypeptide
-found in eukaryotic cells = 80S ribosomes
-made from subunits 60S + 40S

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14
Q

RER

A

-made from flattened fluid-filled sacs of membrane called cisternae
-location of extracellular protein synthesis
-once a protein has been made the membrane pinches off to form a vesicle which can be transported around the cell
-usually found next to the nucleus + sometimes connected to the nuclear envelope.

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15
Q

SER

A

-manufacture and then transport lipids and steroids such as certain hormones
-cells that store large quantities of carbs, proteins and fats including liver and secretory cells have extensive ER

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16
Q

Mitochondria

A

-site of aerobic respiration to produce ATP and energy for the cell
-capsule shaped and made from a double membrane filled with a fluid called matrix
-inner membrane folded into cristae providing a larger surface area for attachment of enzymes
-muscle cells will contain a high number of mitochondria as they need a lot of ATP

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17
Q

Centrioles

A

-only found in ANIMAL cells
-found in pair near nucleus usually at right angles
-each is a bundle of 9 microtubules making hollow cylinders, sometimes called a centrosome
-used when a cell divides
-move to opposite ends and produce the microtubule spindle that will attach to the chromosomes and pull them apart

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18
Q

Lysosomes

A

-small temporary unit, membrane bound vacuoles
-contain and isolate digestive enzymes, usually lysozymes
-used for breaking down old organelles
-can fuse with cell membrane and release it’s enzymes out of the cell
-used in programmed cell death, autolysis, when a cell self destructs

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19
Q

Golgi apparatus/body

A

-stacks of membrane bound sheets
-golgi receives vesicles containing proteins made in the RER
-golgi modifies and packages the proteins
-release the modified proteins into vesicles to be transported around the cell or released at the cell membrane by exocytosis

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20
Q

Exocytosis

A

-contents of the vesicles e.g enzymes, hormones etc. are released out of the cell
-ACTIVE process REQUIRES ENERGY

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21
Q

Endocytosis

A

-material that needs to move into the cell becomes surrounded by an area of cell membrane that then buds off into the vesicle
-ACTIVE process REQUIRES ENERGY

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22
Q

Cytoskeleton

A

-fibrous network that fills the cytoplasm
-gives cells structure
-moves and holds structures like organelles
-made from microtubules and protein microfilaments like actin

23
Q

Cytoplasm

A

-most cellular metabolism
-mostly made from water
-cytosol is the ‘soup’ in which the organelles reside
-cytoplasm = cytosol + organelles

24
Q

Cell wall

A

-ONLY FOUND IN PLANT CELLS
-provides strength and support
-freely permeable, doesn’t control what comes in and out of the cell
-made of layers- middle lamella which contains pectin and the cellulose microfibrils. Also needs calcium to strengthen structure
-linked together by gaps in cell walls called plasmodesmata

25
Plasmodesmata
-small channels that directly connect the cytoplasm between two adjacent cells -allow for direct transport between cells ONLY IN PLANT CELLS
26
Functions of cell wall
1- transport- gaps between cellulose fibres make it permeable to water and ions- space outside= apoplast 2- mechanical strength- strong. when vacuole is full, cell contents push against cell wall, it resists expansion and cell is turgid 3- communication between cells- plasmodesma occurs when there is no cellulose thickening between two cells. the network of cytoplasm in connected cells is symplast. important in water transport through a plant
27
Chloroplasts
-site of photosynthesis, found in large concentration in palisade mesophyll layer -contain chlorophyll, 70S ribosomes and circular DNA -double membrane bound capsule, inner membrane folded into thylakoids which are staked up to form granum -provides a large surface area for chemical reactions to occur -linked by lamella and surrounded by liquid called stroma.
28
Vacuole
-animal cells sometimes have small temporary vacuoles, but plant cells have a large permanent vacuole -filled with cell sap = dissolved substances in water -used to help maintain the cell shape -also used for storage
29
Tonoplast
-name of the membrane that surrounds the vacuole -controls what enters and leaves the vacuole and therefore controls the cell's osmotic potential
30
Prokaryotic- cell wall
-prevents cell bursting -gives bacteria it's shape -made of peptidoglycan which is a combination of polysaccharide and protein -2 types of cell wall
31
Prokaryotic - capsule
-only on some bacteria -made from various different molecules such as starch or glycolipids -protects bacterium from drying out in certain conditions, or being discovered by the immune system
32
Prokaryotic - cell membrane
-The cell membrane, also known as the plasma membrane, is a double layer of lipids and proteins that surrounds a cell. It separates the cytoplasm (the contents of the cell) from the external environment.
33
Prokaryotic - mesosome
-One difference between eukaryotic and some prokaryotic cell membranes is that they can have a section that folds inwards to form a mesosome.​ -A mesosome performs the same function as a mitochondrion.​ -Prokaryotes don’t have any membrane bound organelles so don’t have mitochondria.
34
Prokaryotic - Nucleoid
-Prokaryotes don’t have a nucleus.​ -But they still have DNA which is in the form of one long single strand called the nucleoid.​ -This is not in a membrane but just free in the cytoplasm.
35
Prokaryotic - plasmids
-Small circular loops of DNA.​ -They can be transferred between bacteria.​ -Code for a specific trait.
36
Prokaryotic - ribosomes
-Smaller that eukaryotic ribosomes.​ -These are 70S made from a 30S and 50S subunits.​ -They have the same function as in eukaryotes
37
endosymbiont theory
-The endosymbiont theory is a widely accepted theory that explains how Eukaryotic cells evolved from Prokaryotic cells. -Theory proposed that the main organelles of the eukaryotic cell were actually primitive prokaryotic cells that had been engulfed by a different, bigger prokaryotic cell.
38
Prokaryotic - flagella and pili
-Some bacteria have flagella for movement.​ -Made from protein fibres called flagellin which are spun around like a motor.​ -Some bacteria have thousands of small structures called pili on the outside.​ -They are use to help the bacteria reproduce and communicate.
39
Prokaryotic- Gram staining
-able to see the 2 cell walls -gram positive bacteria and gram negative bacteria
40
Organelles are interrelated
1.Nucleus – synthesising rRNA (this is used for protein)​ 2.rRNA released through pore ​ 3.rRNA fuses with RER as a ribosome – site of protein synthesis​ 4.Vesicle (containing protein) pinched off ER​ 5.Vesicle fuses with Golgi body – protein is modified and packaged​ 6.Vesicle pinched off Golgi body – taking modified protein to cell membrane​ 7. Vesicle fuses with cell membrane for exocytosis to take place – protein leaves cell
41
4 Types of tissues
1- Epithelial tissue 2- Nervous tissue 3- Muscle tissue 4- Connective tissue
42
4 Types of epithelial tissue
1-cilliated 2-squamous 3-columnar 4-cuboidal
43
3 Types of muscle
1-straited 2-smooth 3-cardiac
44
5 Types of connective tissue
1-dense 2-adipose 3-areolar 4-compact bone 5-blood
45
stratified
cells are in layers
46
Squamous epithelial tissue
-A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basal membrane. -thin, flat cells -Examples of Simple:​ Capillary lining, Alveoli​ -Examples of Stratified:​ Lining of Mouth, Lining of Vagina
47
Cuboidal epithelial tissue
-short, cylindrical cells, appear hexagonal in cross section -Examples of Simple:​ Lining of Proximal and Distal Convoluted tubules in Kidney nephrons​ -Examples:​ Mammary glands​, Sweat glands​, Salivary glands
48
Columnar epithelial tissue
-Long, or column-like cylindrical cells, which have a nucleus at the base -Examples of Simple:​ Digestive tract, Upper respiratory tract​ -Examples:​ rectum, male urethra, ducts of salivary glands
49
Ciliated epithelial tissue
-Cuboidal or Columnar epithelium can be ciliated. Cilia are fine hair-like projections that move mucus in a specified direction -Examples:​ Respiratory tract (bronchioles), Vas deferens, Oviducts (fallopian tubes)
50
Basement membrane
-The basement membrane is a thin, pliable sheet of extracellular matrix that supports the tissue and acts as an anchoring platform. It sits between the epithelial cells and the connective tissue. -It is jointly made by the epithelium and the underlying connective tissue
51
Smooth muscle
-look for smooth appearance and pale nuclei -examples: walls of arteries and veins, around glands
52
Striated muscle
-look for striped appearance and darker nuclei -examples: stomach, small intestine, large intestine, rectum
53
Cardiac muscle
-look for a more chaotic appearance with intercalated discs, cross striations and branching

Biology Unit 1- 12th May (6 decks)

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