Biology 11 IB

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Biology 11 IB

• 2.3 eukaryotic CelLs

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Assessment Statements

• 2.3.1 Draw and label a diagram of the
  ultrastructure of a liver cell as an example of
  an animal cell
• 2.3.2 Annotate the diagram with the functions of
  each named structure
• 2.3.3 Identify structures from 2.3.1 in electron
  micrographs of liver cell
• 2.3.4 Compare prokaryotic and eukaryotic cells
• 2.3.5 State three differences between plant and
  animal cells
• 2.3.6 Outline two roles of extracellular
  components

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Eukaryotic Cells

• Eu True, karyon meaning kernel, referring to
  the nucleus ? True Nucleus
• The general size of a eukaryotic cell is about
  5-100 um.
• The ribosomes are larger than eukaryotic cells
  (80S versus 70S ribosomes)
• Compartmentalization allows chemical reactions to
  be separated increasing the efficiency of the
  cell

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Organelles

• Endoplasmic Reticulum
• Ribosomes
• Lysosomes (not usually in plant cells)
• Golgi Apparatus
• Mitochondria
• Nucleus
• Chloroplasts (only in plant cells)
• Vacuoles

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Endoplasmic Reticulum

• Extensive netowrk of tubules or channels that
  extends almost eveywhere in the cell from the
  nucleus to the plasma membrane
• Function transportation of materials throughout
  the internal region of the cell

Smooth ER Rough ER
Produces membrane phospholipids and cellular lipids Produces sex hormones (testosterone and estrogen) Detoxifies drugs in the liver Stores calcium ions needed for contraction in muscle cells Transport lipid based compounds Aid the liver in releasing glucose into the bloodstream when needed Involved in protein development and transport (function as support for ribosomes)
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Ribosomes

• Carry out protein synthesis
• Can be free in the cytoplasm or attached to the
  rough ER
• Composed of RNA and protein
• Larger and denser in eukaryotes vs prokaryotes
• Composed of two subunits (80S)

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Lysosomes

• Digestive centers the arise from the Golgi
  apparatus
• Sacs of hydrolytic enzymes the catalyze the
  breakdown of proteins, nucleic acids, lipids and
  carbohydrates
• Fuse with old or damaged organelles to recycle
  the components
• Responsible for breaking down materials brought
  into the cell by phagocytosis
• The interior of a functioning lysosome is acidic

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Golgi Apparatus

• Composed of flattened sacs called cisternae
• Functions in the collection, packaging,
  modification, and distribution of materials
  synthesized in the cell
• One side is always close to the rough ER (cis
  side) receiving products from the ER
• Movement occurs to discharge the product from the
  opposite (trans) side. Small sacs, called
  vesicles, can be seen coming off the trans side
  carrying modified materials to wherever they are
  needed inside or outside the cell.
• Prevalent in glandular cells that manufacture and
  secrete substances (ex. in the pancreas)

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Mitochondria

• Have their own DNA! (a circular chromosome
  similar to that in bacterial cells)
• Double membrane smooth on the outside, folded
  on the inside
• Reactions within produce usuable cellular energy
  (ATP), where it gets its nickname the
  powerhouse
• Produces and contains its own ribosomes (70S)
• Cells that have high energy requirements, such as
  muscle cells, have large numbers of mitochondria

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Nucleus

• Isolated region housing the DNA in the form of
  chromosomes (strands of DNA wrapped around
  histones protein)
• Double membrane ? nuclear envelope (allows for
  compartmentalization providing an area where
  DNA can carry out its functions and not be
  affected by processes occurring in other parts of
  the cell)
• Nuclear pores in the nuclear membrane allow
  communication with the cells cytoplasm

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Chloroplasts

• ONLY in algae and plant cells!
• Double membrane, about the same size as
  mitochondrion
• Has its own DNA (in the form of a ring) and 70S
  ribosomes
• Grana (pile of thylakoids) stroma (fluid
  containing enzymes necessary for photosynthesis)
• Can reproduce independently of cell

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Vacuole

• Storage organelles the usually form from the
  Golgi apparatus
• Occupy large space in plant cells
• Can store food, metabolic wastes and toxins, and
  water
• Enable cells to have higher surface area to
  volume ratios
• In plants, they allow an uptake of water
  providing rigidity

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Centrosome

• Generally contains a pair of centrioles which are
  involved in assembling microtubules (important in
  providing cell structure and allowing movement)
• Important to cell division
• Higher plant cells produce microtubules even
  though they do not have centrioles
• Located at one end of the cell, close to the
  nucleus

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Prokaryotic Cells Eukaryotic Cells
DNA in ring form without histones DNA with protein as chromosomes/chromatin
DNA free in cytoplasm (nucleoid region) DNA enclosed in a nuclear envelope
No mitochondria Mitochondria present
70S ribosomes 80S ribosomes
No internal compartmentalization to form organelles Internal compartmentalization present to form many types of organelle
Size less than 10 micrometers Size more than 10 micrometers
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Similarities of prokaryotic and eukaryotic cells

1. Both types of cell have some sort of outside
   boundary that always involves a plasma membrane
2. Both types carry out all the functions of life
3. DNA is present in both cell types

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eukaryotic cells
Plant Cells Animal Cells
Exterior of cell includes an outer cell wall with a cell membrane just inside Exterior of cell includes only a cell membrane
Chloroplasts present in the cytoplasm No chloroplasts
Possess large centrally located vacuoles Vacuoles are usually small or non existent
Store carbohydrates as starch Store carbohydrates as glycogen
Do not contain centrioles within a centrosome area Contain centrioles within a centrosome area
Fixed, often angular shape (because of rigid cell wall) Cell is flexible and usually round