Unit #1 - Interdependence What do living things need?

I. Studying Life Biology – the study of life (bios – “life”, -logy – “study of”). Biologist – someone who uses scientific methods to study living things.

A. Characteristics of Living Things All living things share the following : 1. Are made up of units called cells. Cell – a collection of living matter enclosed by a barrier that separates the cell from its surroundings. -Cells are the basic/smallest units of life. Unicellular – single-celled organisms. Multicellular – many-celled organisms.

Characteristics of Living Things 2. Can reproduce. Sexual – 2 parents create genetically different offspring. Asexual – one parent produces a clone of itself. 3. Are based on a universal genetic code : the molecule DNA.

Characteristics of Living Things 4. Growth and development. Metabolism – combination of chemical reactions in which an organism uses materials to carry out life functions. 5. All obtain & use materials & energy. 6. All respond to their environment. Stimulus – a signal to which an organism responds; can be internal or external.

Characteristics of Living Things 7. Maintain a stable internal environment. Homeostasis – process by which an organism keeps its internal conditions fairly constant in order to survive. 8. In general, they change over time.

B. Other Branches of Biology 1. Zoology – study of animals. 2. Botany – study of plants. plants. 3. Paleontology – study of ancient life. of ancient life.

C. 4 types of organic molecules in living things : 1. Carbohydrates – compounds made up of carbon, hydrogen, & oxygen atoms, usually in a ratio of 1 :2 :1, ex : sugars, starches, & cellulose. **Living things use carbohydrates as their main source of energy.** -Energy for cell activities comes from the immediate break-down of sugars, such as glucose. -Extra sugar is stored as complex carbohydrates known as starches.

Lipids 2. Lipids – macromolecules made mainly from carbon & hydrogen atoms & glycerol; includes fats, oils, waxes, phospholipids, & steroids. -Used to store energy, insulate, repel water, & form membranes.

Nucleic Acids 3. Nucleic acids – macromolecules containing hydrogen, containing hydrogen, oxygen, nitrogen, oxygen, nitrogen, carbon, & phosphorous. carbon, & phosphorous. -Contain genetic/hereditary info. -Are assembled from nucleotides – monomers of nucleic acids made up of a : 1. 5-carbon sugar 2. Phosphate group 3. Nitrogenous base.

2 Major Types of Nucleic Acids : A. DNA – (deoxyribonucleic acid) carries instructions that control the activities of a cell. B. RNA – (ribonucleic acid) uses those instructions to make/build proteins.

Proteins 4. Proteins – macromolecules that contain nitrogen, carbon, hydrogen, & oxygen. -Are made up of amino acids – compounds with an amino group (-NH2) on one end & a carboxyl group (-COOH) on the other end. -Amino acids are the building blocks of proteins. -20 different amino acids are used to build proteins. Different combinations = different proteins.

Each protein has a specific role, ex : 1. Control the rate of reactions & regulate cell processes. & regulate cell processes. 2. Form bones, muscles, & hormones. 3. Transport substances in or out of cells & fight disease : antibodies. out of cells & fight disease : antibodies. Enzymes – proteins that help control chemical reactions. Can speed up reactions, ex : Digestion.

D. Other nutrients needed by living things Nutrients – substances in food that provide the raw materials and energy the body needs for essential processes. Nutrients are keep the body’s cells functioning, growing, and replicating. -Are made up of chemical elements including carbon, oxygen, hydrogen, nitrogen, and phosphorous.

Vitamins 1. Vitamins – chemical compounds needed by the body in small amounts to strengthen the immune system, grow, and repair damaged cells/tissues. -Vitamins are supplied to the body by a well balanced diet.

Problems related to vitamin deficiency : Vitamin A – Liver problems, hair loss, rough skin. Carrots are a good source. Vitamin B2 – Eye problems and cracking skin. Vitamin B3 – Mental problems, rash, and diarrhea. Vitamin C – Sore mouth, bleeding gums, and bruises. Vitamin D – Bowed legs, rickets, & poor teeth.

Minerals 2. Minerals – chemical compounds needed in small amounts to help form needed in small amounts to help form important cell parts. important cell parts. -Mineral deficiency can cause : a. Iron – used for blood. Risk = Anemia, which causes extreme fatigue & bruising. which causes extreme fatigue & bruising. b. Calcium – used for strong bones and teeth. Risk = Osteoporosis later in life. c. Magnesium – used for bones and teeth. Risk = Severe muscle twitches that can Risk = Severe muscle twitches that can become very painful. become very painful. d. Iodine – used for making chemicals in the thyroid (found in salt). Risk = development of a goiter (abnormally enlarged thyroid). e. Sodium – (NaCl or salt) used for muscle contractions and nerve messages.

Water 3. Water – fluid made up of hydrogen and oxygen that hydrogen and oxygen that makes up approximately 50-60% of the human body. makes up approximately 50-60% of the human body. How much water does the average adult need? Answer : 2 liters per day (8 glasses) The body uses water to : Re-hydrate the body by Re-hydrate the body by replenishing liquids. replenishing liquids. Flush out toxins. Flush out toxins. Control body temperature. Control body temperature.