What is Biology?

What is Biology, you ask? Biology is the study of life. Living things are called organisms. Organisms include bacteria, protists, fungi, plants, and animals. Viruses are not alive – they are not organisms. 2

The seven characteristics of life All life is made of cells. All life must reproduce. All life has heredity based on one universal genetic code (DNA). All life has metabolism. All life must respond to environmental stimuli. All life has homeostasis; it must maintain a stable internal environment. All life must evolve; that is, species must change over time. 3

All organisms are made of cells 4

Cells are the building blocks of life. All cells come from pre-existing cells. 5 Viruses (in red here) are not made of cells; they are not alive. Viruses (in red here) are not made of cells; they are not alive.

The cell theory states that  all living things are made up of cells;  basic units of structure and function in living things are cells  that new cells can only be produced from living, existing cells.

Biochemical Reactions

Cells can undergo chemical reactions that release energy from carbon-containing compounds (organic) as food. There are 3 major classes of organic molecules: Carbohydrates Proteins Lipids

Carbohydrates Include sugar – C 6 H 12 O 6 Formed from photosynthesis Broken down in cellular respiration Equation: Photosynthesis 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2 Equation: Cellular Respiration P + ADP + C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + ATP

Proteins Needed: to access energy stored in cells to build cell structures to regulate rate of chemical reactions

Lipids Commonly known as fats and oils Create membranes of cells that provide sites for essential energy conversions. Refer to figure 1 in the packet

Cell membrane Separates the living from non-living environment. Made of protein and lipid Made of protein and lipid

Cell membrane A cell must be able to obtain food and get rid of wastes through its cell membrane 13

Diffusion The movement of particles from a region of high concentration to a region of low concentration. Examples: perfume in air, smoke in air, sugar in water, oxygen through cell membranes Click here for videovideo

Osmosis Diffusion of water from an area of high concentration of water molecules to one of low concentration across a partially permeable membrane. Partially permeable means only some things can pass, not everything: usually small molecules with no charge, like H 2 O, CO 2, & O 2. “High” water concentration means that there are a lot of water molecules per some unit of volume. “Low” water concentration means that there is a lot of something dissolved in the water, so fewer molecules of water. 15 video

Comparison of Photosynthesis and Cellular Respiration Discuss Table 1 Photosynthesis 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2 Cellular Respiration P + ADP + C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + ATP video

All life has metabolism Cellular Respiration (in Mitochondria) Through respiration, cells release the chemical energy stored in foods created by photosynthesis. 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + 36 ATP 17

All life has metabolism Sunlight is the ultimate energy for life on Earth. Photo-synthesis is carried out in the chloro- plast of producers such as algae, phy- toplankton, plants.

Asexual and Sexual Reproduction

Asexual Reproduction One parent passes copies of all its chromosomes to each of its offspring. Organisms produce new cells by mitosis. Mitosis is the process of nuclear division in which 2 new daughter cells each receive a complete set of chromosomes. Offspring are genetically identical to each other and the parent. Examples: Refer to table 1 video

Sexual Reproduction Involves two parents The offspring receives half of its chromosomes from the father and half from the mother. Gametes are sex cells (eggs – sperms) Meiosis produces gametes (1/2 # chromosomes) Upon fertilization, full number of chromosomes is restored with the formation of a zygote.

A zygote contains all the information necessary for growth, development, and reproduction. The zygote will be similar but not identical to its parents.

All organisms must reproduce For sexual reproduction For asexual reproduction Gametes video

Punnett Squares Genotype – genetic characteristics carried by an organism. Phenotype – the way an organism looks and behaves. Alleles – genes that exists in alternative forms. The allele combination determines its genotype. Dominant Recessive

Punnet squares predict probabilities of outcomes. Gametes produced by each parent pea plant are shown along the top and left side. Remember: when the germ cell that produces the sperm or egg divides, the 2n (diploid) number of chromosomes is split in half: Tt becomes T and t. T = dominant t = recessive

All life has heredity in DNA Punnet squares predict probabilities of outcomes. ¼ of offspring are TT. ½ of offspring are Tt. ¼ of offspring are tt. But ¾ of offspring are tall, and only ¼ are short (3:1 ratio). T = dominant t = recessive The dominant characteristic usually overpowers the recessive one. The dominant characteristic usually overpowers the recessive one.

Two pink-flowering plants are crossed. The offspring flower are as follows: 25% red, 25% white; 50% pink. What pattern of inheritance does flower color in these flowers follow? A. dominance B. multiple alleles C. incomplete dominance D. recessiveness E. polygenic trait

All life has heredity in DNA Pedigree charts relate to punnet squares Square = man Circle = woman Filled = disease Half filled = carrier Open = healthy

DNA and Proteins

All organisms contain DNA. DNA (deoxyribonucleic acid) carries the genetic code for all organisms. Four nucleotides: Nitrogenous bases A - adenine T – thymine G – guanine C - cytosine 30

All life has heredity in DNA DNA The code of life