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IB Biology > Cell Biology - 1.2 Ultrastructure of cells > Flashcards

Cell Biology - 1.2 Ultrastructure of cells Flashcards

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1
Q

Prokaryotic cells

A

Bacteria and Archaea

  • No nuclear membrane (ie a nucleoid) (no definite nucleus) - DNA is stored in the cytoplasm
  • DNA is not bound to proteins
  • Division by binary fission (ie asexual)
  • all unicellular (single-celled)
  • VERY SMALL

Pili – shown as single lines
Flagella – shown as thicker and significantly longer lines than the pili
Ribosomes – labelled as 70S
Cell wall – labelled as being composed of peptidoglycan; thicker than cell membrane
Shape – appropriate for bacteria chosen

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2
Q

Organelles

A

Tiny structures within the cytoplasm that preform specific jobs eg. ribosomes

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3
Q

Eukaryotic cells

A

All other life (BUT BACTERIA AND ARCHAEA) eg. animals/plant/Protoctista (protist)/Fungal cells

  • has a nucleus.
  • bigger than a prokaryote
  • division by binary fission, mitosis or meiosis
  • unicellular or multicellular
  • contain membrane-bound organelles (and form spindles during mitosis and meiosis)
  • have a compartmentalized cell structure
  • eukaryote chromosome (enclosed within a nuclear membrane) is a folded length of SNA - wound around proteins called histones
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4
Q

Cell membrane

A

Responsible for regulating what materials move into and out of the cell

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5
Q

Nucleoid

A

DNA with ends that come together to form a circle (and its NOT wrapped around proteins)

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6
Q

Cytoplasm

A

Gel-like fluid substance (mostly water with many dissolved molecules), site of metabolic reactions

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7
Q

Ribosomes

A

complexes of RNA and protein that are responsible for polypeptide synthesis and build proteins during translation

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8
Q

Plasmid (Structure found in SOME but not ALL prokaryotic cells)

A

Extra pieces of small circular DNA that can be shared between bacteria (by conjugation), often contain genes for antibiotic resistance

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9
Q

Cell wall

A

provides shape and allows the cell to withstand turgor pressure with bursting

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10
Q

Pili (Structure found in SOME but not ALL prokaryotic cells)

A

enable the cell to attach to surfaces, swap DNA with other cells and may be used to harpoon DNA in the environment

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11
Q

(slime) Capsule (Structure found in SOME but not ALL prokaryotic cells)

A

A thick polysaccharide layer Helps the cell keep from dehydrating (desiccation), phagocytosis and adhere to surfaces

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12
Q

Flagellum (Structure found in SOME but not ALL prokaryotic cells)

A

Long extensions containing a motor protein that enable movement - used in cell locomotion

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13
Q

Cytoplasm

A

The internal fluid component of the cell

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14
Q

Cytoplasm

A

The internal fluid component of the cell - gives the cell shape

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15
Q

Compartmentalized

A

= a separate section of a structure (cell) in which certain items ( can be kept separate from others) - occurs in Eukaryotic cells BUT NOT prokaryotic cells

Advantage = an organelle can create a compartment with controlled conditions - tailored to the specific functions of the organelle (a microenvironment)
- they are super-efficient

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16
Q

Process of binary fission

A
  1. Prepare for division (must have enough energy and resources)
  2. DNA is replicated semi conservatively (and depends on the complementary base pairing
  3. the two DNA loops attach to the membrane + cell growth
    4/5. the membrane elongates and pinches off (cytokinesis) forming two separate cells
  4. Two cells = The two daughter cells are genetically identically
    = In ideal conditions this can occur every 20 minutes
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17
Q

Asexual reproduction

A

= offspring arise from a single parent cell or organism
= the offspring are genetically identical to the parent

(Binary fission and mitosis are mechanisms of asexual reproduction)

18
Q

eukaryote cells -> Animal cells eg. skin, muscle, nerve etc. cells

A
  • Multicellular, specialized cells
  • Possess nucleus and membrane-bound organelles
  • lack cell walls
  • heterotrophic
19
Q

eukaryote cells -> Plant cells eg. leaf, root, skin etc. cells

A
  • Multicellular, specialized cells
  • possess nucleus and membrane-bound organelles
  • contain chloroplasts
  • cell walls of cellulose
  • Autotrophic
20
Q

eukaryote cells -> Protoctista (protist) cells eg. amoeba, paramecium, chlorella etc. cells

A
  • mostly free-living single cells

- some autotrophic, some heterotrophic

21
Q

eukaryote cells -> Fungal cells eg. yeasts, mushrooms, mould etc. cells

A
  • possess a nucleus and membrane-bound organelles

- cell walls of chitin

22
Q

what does membrane-bound organelles mean?

A

The small structure inside the cell membrane that carries out various important cellular functions - organelles are bound by a membrane that allows for things to move in and out of the cell

23
Q

Nucleus

A

the control centre containing all genetic information (DNA) for the cell which controls all cell activities - contains the nucleolus

24
Q

ROUGH endoplasmic reticulum

A

series on connected flattened membranous sacs that play a central role in the synthesis and transport of proteins

  • has ribosomes
  • closer to the nucleus
25
Q

SMOOTH endoplasmic reticulum

A

smooth ER lacks ribosomes and is not involved in protein synthesis

MAIN FUNCTIONS = the synthesis of phospholipids and cholesterol and the syntheses and repair of membranes

26
Q

Golgi apparatus

A

Package and release proteins from the cell:

  • modifies, sorts, concentrates and packs proteins from the RER into sealed droplets called vesicles - dispatched into either the lysosomes (organelles in the cell), Plasma membrane of secretion to outside of the cell
27
Q

Lysosome

A
  • Small spherical organelles enclosed by a single membrane
  • contain enzymes that work in o2 poor areas and lower pH
  • Enzymes digest large nutrient molecules and/or degrade and recycle the components of the cell’s own organelles when they are old/damaged (or the cell is starving - lack of nutrients)
28
Q

Mitochondria

A
  • Location of aerobic cellular respiration which is used to make ATP - ATP is then used to duel the exocrine gland cells protein synthesis, active transport and exocytosis

(cells convert food to energy via respiration)

29
Q

Small vacuoles (vesicles) - can not be seen on lab microscope

A

store food and chemicals and floating in the cytoplasm (Animals cells = many small)
(Plan cells = ONE large central vacuole)

30
Q

Centrioles

A

Makes spindle for cell division

31
Q

Animal cells (organelle list)

A 
Cell membrane
cytoplasm
nucleus 
mitochondria
ribosomes
lysosome
smooth ER
rough ER
Golgi bodies
centrioles
small vacuoles
nucleolus
32
Q

Plant cells (organelle list)

A 
Cell membrane
cytoplasm
nucleus
chloroplasts
cell wall
large vacuole
mitochondria
smooth ER
rough ER
ribosomes
lysosome
golgi bodies 
nucleolus
33
Q

Fungal cells (organelle list) = can be unicellular or multicellular

A
  • have complex cellular organisation –> DON’T HAVE chloroplasts or chlorophyll
Cell membrane 
cytoplasm 
nucleus 
mitochondria
ribosomes 
small vacuoles
cell wall
golgi bodies
34
Q

Protist cells (organelle list)

A 
Cell membrane
cytoplasm
nucleus
mitochondria
ribosomes
small vacuoles
chloroplasts
eyespot
cilia or flagella
golgi bodies
contractile vacuole
35
Q

Cell size

A

Cells are usually measured in micrometres (μm) (1000 μm = 1 mm)

Very small structures (and/or virsus) are measured in nanometers (nm) (1,000,000nm = 1mm or 1000nm = 1μm)

(Plant cells are normally larger than animals cells)

36
Q

Resolution (in terms of microscopes)

A

= is the smallest interval distinguishable by the microscope which then corresponds to the degree of detail visible in an image created by the instrument

ie. magnification is = but the resolution is better with the electron microscope

Resolution is the shortest distance between two points that can be distinguished

37
Q

Ultrastructure

A

fine structure, especially within a cell, that can be seen only with the high magnification obtainable with an electron microscope.

38
Q

Light microscopes

A
  • combination of lenses to magnify objects up to 1000x (eg. 10x eyepiece and e 40x objective = 400x magnification)
  • Specimens viewed must be thin and mostly transparent as light is focused up through the specimen
  • live specimens (eg. bacteria) can be viewed
  • Resolution is the shortest distance between two points that can be distinguished (resolution is 0.2μm)
39
Q

Electron microscopes

A
  • uses a beam of electrons (rather than light) to produce an image
  • magnification = 100,000-250,000 x
  • specimens must be sections/placed on a special disc in a vacuum (live specimens can NOT be viewed)
  • Resolution is 0.001μm

Two types:

1) Transmission EM (which can view organelles and micro-structure of cells)
2) scanning EM (which can view the outside surface features of cells and tissues

40
Q

Calculation of Magnification:

A

To calculate the linear magnification of a drawing or image, the following equation should be used:

Magnification = Image size (with ruler) ÷ Actual size (according to scale bar)

41
Q

Calculation of Actual Size:

A

To calculate the actual size of a magnified specimen, the equation is simply rearranged:

Image size (with ruler)/measured length ÷ Magnification = Actual/total Size

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