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AS BIO UNIT1 > 1.2 Cell Structure > Flashcards

1.2 Cell Structure Flashcards

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1
Q

1mm to 1um to 1nm

A

x1000, x1000

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2
Q

1nm to 1um to 1mm

A

/1000, /1000

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3
Q

Define magnification

A

The number of times an image is compared with the real size of an object

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4
Q

Magnification equation

A

mag = size of image
———————
actual size

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5
Q

What is the Golgi body? What is its function?

A
  • formed from vesicles from the RER fusing
  • made of a stack of flattened membrane bound cavities
  • package and modify proteins, package secretory enzymes, secrete carbs and glycoproteins, transport and store lipids, form lysosomes
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6
Q

What is endoplasmic reticulum?

A
  • elaborate system of parallel double membranes forming flattened sacs with fluid filled spaces called cisternae
  • RER connected to nuclear envelope
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7
Q

What is RER and its role?

A
  • ER with ribosomes on surface (site of protein synthesis)
  • isolate and transport proteins made in the ribosome
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8
Q

What is SER and its role?

A
  • no ribosomes
  • more tubular
  • synthesis and transport of lipids and steroids
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9
Q

What is the nucleus and nucleolus? What are their roles?

A
  • spherical, 10-20um in diameter
  • bounded by 2 membranes called the nuclear envelope which has pores to allow mRNA and ribosomes to exist their site of synthesis and go to the cytoplasm
  • nucleoplasm contains chromatin (coils of DNA bound to protein)
    -nucleolus is the site of formation of rRNA
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10
Q

What is mitochondria? What’s its role?

A
  • double membrane bound organelle
  • produce ATP energy via respiration
  • organic matrix containing lipids and proteins and cristae which provide SA for enzymes involved in AR
  • large surface area to volume ratio = efficiency
  • 70S ribosomes allow protein synthesis
  • small amounts of DNA
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11
Q

What are ribosomes and their role?

A
  • assembled in nucleus from rRNA and protein
  • sit of translation of the genetic code
  • 2 sub units for tRNA and mRNA attachment
  • assemble proteins
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12
Q

Chloroplasts and their role

A
  • photosynthesising tissue
  • 2 membranes: chloroplast envelope
  • stroma fluid, able to replicate
  • thylakoids are flattened sacks that stack to from granum (chlorophyll found here)
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13
Q

What are centrioles and their role?

A
  • star shaped tubes found outside the nucleus
  • not in higher cells of plants
  • synthesise microtubules of the spindle in CD
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14
Q

What are lysosomes?

A
  • small, temporary vacuoles surrounded by a single membrane formed by being pinched off the Golgi body
  • contain and isolate digestive enzymes and fuse and digest worn out cell parts
  • digest materials engulfed by cell (ie bacteria)
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15
Q

Structure of the cell wall

A
  • cellulose
  • held together in microfibrils, aggregated to fibres and embedded in a polysaccharide matrix called pectin
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16
Q

Outline the functions of the cell wall

A
  • transport: the gaps between fibres make cell wall fully permeable to water and dissolved molecules/ions. Called apoplast and is main pathway for water
  • mechanical strength: strong and resists expansion when vacuole is full, making cell turgid and supportive
  • communication: cell walls have pores through which strands of cytoplasm called plasmodesmata pass ( cytoplasmic connections between adjacent plant cells). Occurs where there is no cellulose thickening
17
Q

Explain division of labour in creation of proteins/enzymes

A
  • nucleus contains chromosomes in which the DNA encodes protein
  • nuclear pores in the nuclear envelope allow mRNA molecules transcribed off the DNA to leave the nucleus and attach to ribosomes in RER
  • ribosomes contain rRNA transcribed from DNA in nucleolus
  • protein synthesis occurs on ribosomes - primary structure
  • polypeptides transported through RER and packaged into vesicles. Bud off and carry to Golgi body to be chemically modified and folded
  • Golgi body produces vesicles w newly synthesised proteins - lysosomes or secretary vesicles for exocytosis
18
Q

What are viruses?

A
  • acellular organisms
  • no organelles, cytoplasm or chromosomes
  • exist as inert ‘virions’ until in a host cell which they take over and multiply
  • core of nucleic acid (RNA or DNA), surrounded by a protein coat called the capsid
19
Q

What are the viruses that attack bacteria?

A
  • bacteriophage
  • ie T2 which attacks E. coli
20
Q

Define differentiation and explain how it occurs

A
  • the development of a cell into a specific type
  • turn genes on and off
  • unspecialised cells are called ‘packing cells’
21
Q

What is epithelial tissue?

A
  • tissue that covers and lines the internal and external surfaces of the body
  • no blood vessels but can have nerve endings
  • sit on a basement membrane made of collagen and protein
  • usually a secretory or protective function
22
Q

What is cuboidal epithelial tissue?

A
  • simplest form
  • 1 cell thick
  • on the proximal convoluted tubule of the kidney nephron and ducts of the salivary glands
23
Q

What is columnar epithelial tissue?

A
  • also known as ciliated
  • elongated cells that line the tubes substances move through (oviduct of Fallopian tubes and trachea)
  • cilia on end beat
24
Q

What is squamous epithelium tissue?

A
  • flattened cells
  • walls of alveoli and lime the renal capsule of the nephron
25
Q

Describe skeletal muscle tissue

A
  • attached to bones and generates locomotion on mammals
  • bands of long cell fibres
  • tires easily
  • has voluntary muscles
    —> is striped
26
Q

Describe smooth muscle

A
  • spindle shaped that contract rhythmically
  • skin, blood vessels, digestive & respiratory tracts
  • involuntary muscles
    —> not striped
27
Q

Describe cardiac tissue

A
  • mix of smooth and skeletal - striped but lacks the long fibres
  • contracts rhythmically
  • does not tire
28
Q

What is connective tissues?

A
  • connects, supports or separates tissues and organs
  • elastic and collagen fibres in extra cellular fluid or matrix
  • fat cells (adipocytes) between fibres
29
Q

What is chromatin?

A

Coils of DNA bound to histone proteins

30
Q

2 differences between ribosomes in animal cells and ribosomes in prokaryotic

A
  • animals are 80S and prokaryotic are 70S
  • ribosomes not attached to ER in the prokaryotes
31
Q

Why do some mitochondria appear different to each other?

A

Cut in a different plane or angle

32
Q

2 structures found in prokaryotic cells also found in mitochondria

A
  • loop of DNA
  • 70S ribosomes
  • both have plasma cell membranes
33
Q

Describe two differences between mitochondria and prokaryotic cells

A
  • mitochondria has double membrane, no cell wall, no mesosomes and no flagellum

AS BIO UNIT1 (6 decks)

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