Chapter 2: How Cells Function

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Chapter 2 How Cells Function
2.1 Chemical reactions take place inside
cells 2.2 Cells capture and release energy 2.3
Materials move across the cells membranes
Will learn -About the types of elements found in
all cells -the functions of the large molecules
in the cell -Why water is important to the
activities of the cell

• Have already learned
• -All living things are made of cells
• -Cells need energy to sustain life
• -Plant and animal cells have similarities and
  differences

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Warm-up Questions

• True for animal cells, plant cells, or both?
• They need energy to sustain life
• They have organelles
• They have cell walls

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All cells are made of the same elements

• The matter that makes up the cell itself is too
  small for a light microscope
• All matter broken down into elements, each with
  own characteristics
• Example
• Oxygen, on Earth, found as colorless odorless gas
• 25 elements (of 100 on Earth ) are essential for
  life
• 6 elements account for about 99 of the mass of
  our bodies!
• Oxygen 65, Carbon 18.5, Hydrogen 9.5,
  Calcium 1.5, Phosphorus 1.0, all other 19
  1.2

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Elements
RANK- simple to complex cell, atom, molecule

• Smallest unit of an element atom
• In our body
• mostly in the form of compounds atoms of two or
  more elements chemically bonded
• O O O2 C O O CO2
• Most cellular activities atoms and molecules
  interacting via chemical reactions (bonds broken
  and formed to make new molecules)
• Need and release energy! Chemical energy!

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Large molecules for cell function

• 1) Carbohydrates
• 2) Lipids
• 3) Proteins
• 4) Nucleic Acids
• ALL have carbon atoms
• Work together in a cell

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Carbohydrates

• Provide the cell with energy
• Also structure
• Breaking the bonds within the cell releases
  energy
• Simple carbohydrates carbon, oxygen, hydrogen
• Complex carbohydrates simple linked into
  chains starch, cellulose, glycogen
• Plants energy not used makes starches and
  cellulose (cell wall)
• Animals eat plants and get energy

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Lipids

• Fats, oils, and waxes
• Similar to carbohydrates, also made of carbon,
  oxygen, and hydrogen
• Cells use lipids for energy and making structures
• Atoms arranged differently than carbohydrates
• Do not dissolve in water!
• Cannot mix with water
• (important for cell membranes)

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Proteins

• Made of amino acids
• Carbon, oxygen, hydrogen, nitrogen, and sometimes
  phosphorus and sulfur
• Linked into long chains, folded into 3-D shapes
• Structure and function determined by type,
  number, and order of the amino acids
• We get amino acids from food
• meats, eggs, cheese, beans, or created by body
• Different types enzymes (control chemical
  reactions in cells), others support growth and
  repair, muscle movement, fight infections,
  deliver oxygen, form part of the cell membranes

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Nucleic Acids

• Hold instructions for the maintenance, growth ,
  and reproduction of a cell
• DNA Deoxyribonucleic acid
• RNA Ribonucleic acid
• Both made of carbon, oxygen, hydrogen, nitrogen,
  and phosphorus.
• Subunits called nucleotides
• DNA information used by the cell for making all
  the protein the cell needs
• Nucleotide pattern in DNA is copied to RNA, which
  delivers information into the cytoplasmwhere it
  controls chemical reactions and form structures.

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Two thirds of all cells is water

• All chemical reactions inside the cell take place
  in water
• Water makes up
• 46 of bodys mass inside cells
• 23 outside cells in body fluids
• Polar slight positive charge near hydrogen
  atoms, slight negative near oxygen
• Attract opposite charges, repel like
• Many substances dissolve in water

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Water Cells

• Most lipids do NOT dissolve in water
• Cell membrane is made of a double layer of lipids
• Head is polar, tail is not polar
• Cell membrane is a boundary, keeping the inside
  of a cell separate from the outside
• Water-hating tails repel water