Cell Processes and Energy Chemical Compounds in Cells

Cell Processes and Energy

Chemical Compounds in Cells • Element- any substance that can’t be broken down into simpler substances. - Ex: oxygen and nitrogen • Compound- When two or more elements combine chemically, they form a compound. - Ex: water and carbon dioxide

Chemical Compounds in Cells • Watera) Made up of 2 hydrogen and 1 oxygen atoms b) Dissolves chemicals that cells need c) Most chemical reactions in cells could not take place with. OUT water. d) Helps cells keep their size and shape. e) Helps maintain a stable temperature (water temp changes slower than air temp)

Chemical Compounds in Cells • Organic compounds- contain carbon • Inorganic compounds- do not contain carbon - Ex: water and salt

Carbohydrates a) Organic compounds b) energy-rich compound made of carbon, hydrogen, and oxygen c) Ex: starch and sugar, fruit, bread d) Sugar + sugar = starch e) Plant cells use starch to store energy, used for short-term storage f) Important components of cell parts Ex: Cellulose in cell wall

Carbohydrates

Lipids a) Ex: fats, oils, waxes b) energy-rich compounds, made of carbon, hydrogen, and oxygen c) Contain more energy than carbs d) Cells store energy, used for long-term storage e) Cell membranes are made of lipids

Proteins a) Long organic molecules of carbon, hydrogen, oxygen, nitrogen and sometimes sulfur. b) Ex: spider webs, fingernails, feathers, meat, eggs, nuts c) Make up cell organelles d) Proteins called enzymes help chemical reactions occur e) Made of smaller molecules called amino acids f) The order of amino acid linkage determines the protein’s identity

Nucleic Acids a) Long organic molecules of carbon, hydrogen, oxygen, nitrogen, and phosphorus b) Contain cells’ instructions for life c) DNA (Deoxyribonucleic acid)– carries genetic info. , passed from parent to offspring d) RNA (ribonucleic acid)- important for protein synthesis

Molecule Movement • The cell membrane is semi-permeable which means some things can pass through it and others cannot

Molecule Movement • Diffusion- the main way small molecules move across the cell membrane. a) Movement of molecules from high to low concentration b) Cause of diffusion- Molecules bump into each other c) Diffusion of oxygen- more oxygen outside cells than in, so oxygen moves from high to low concentration and enters cells.

Molecule Movement • Osmosis- The diffusion of water from an area of high concentration to an area of low concentration. • Many cellular processes depend on osmosis

Molecule Movement • Osmosis- The movement of water to an area of higher dissolved materials. • Many cellular processes depend on osmosis

Cell Transport a) Passive transport- movement of dissolved materials through a cell membrane without using the cell’s energy. -Ex: Diffusion and osmosis b) Active transport- movement of dissolved materials through a cell membrane using the cell’s energy. Ex: engulfing c) Engulfing- cell wraps around a particle and engulfs it. Also called endocytosis.

Cell Transport d) Why are cells so small? - Smaller cells= more surface area for movement of molecules. Less distance for cytoplasm to span. e) Cells are small so they can be efficient!

Cellular Energy • Every living thing needs energy • The sun is the source of energy for most living things • Photosynthesis a) Photo- light b) synthesis- to put together c) Nearly all living things obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis d) Autotroph- makes its own food e) Heterotroph- obtain food by eating other organisms

Sources of Energy • Nearly all living things obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis.

Photosynthesis- Stage 1 • Photosynthesis: Stage 1 - Capturing the energy in sunlight a) Happens in chloroplasts in leaves b) Pigments- colored chemical compounds that absorb light. Gives leaves their green color c) Cholorphyll- the main pigment in chloroplasts d) See figure on pages 88 -89

Photosynthesis- Stage 2 • Photosynthesis: Stage 2 - Using energy to make food a) Cells need water (absorbed by roots from soil) b) Cells need carbon dioxide (enters leaves from air) c) Stomata- opening in leaves, allows carbon dioxide and oxygen to move in to and out of leaves d) Happens inside chloroplasts, water and CO 2 undergo chemical reactions

Photosynthesis- Stage 2 • Photosynthesis: Stage 2 - Using energy to make food e) Reactions are powered by energy from the first stage f) Plants produce sugar with the formula C 6 H 12 O 6 g) Oxygen is produced and exits through stomata sunlight 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 Carbon Dioxide + Water Sugar + Oxygen

The Two Stages of Photosynthesis • During photosynthesis, plants and some other organisms use energy from the sun to convert carbon dioxide and water into oxygen and sugars.

Cellular Respiration • Cellular Respiration- animal cells break down sugar and obtain energy a) Your cells store energy until you need it • Respiration: Stage 1 a) Happens in cytoplasm b) sugar is broken up into smaller molecules c) oxygen is not involved (Anaerobic) d) Releases a small amount of energy

Cellular Respiration • Respiration: Stage 2 a) Happens in mitochondria b) Small molecules from step one are broken down even further c) Requires oxygen (aerobic) d) Releases LOTS of energy e) See page 92 C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O Sugar + Oxygen Carbon Dioxide + Water

Two Stages of Respiration • During respiration, cells break down simple food molecules such as sugar and release the energy they contain.

Photosynthesis and Respiration • You can think of photosynthesis and respiration as opposite processes.

Fermentation a) Energy-releasing process that DOES NOT require oxygen b) Energy released is much less than that during cell. resp. c) Happens in environments that lack oxygen

Alcoholic Fermentation d) Alcoholic Fermentation - Happens in yeast and single-celled organisms - Releases alcohol - Also releases carbon dioxide and energy - Used to make bread and beer

Lactic Acid Fermentation e) Lactic Acid Fermentation - Happens in your muscles - Produces lactic acid - Makes your muscles sore - Happens when muscle cells use up oxygen faster than it can be replaced