Intro to Biology: Life, Cells, and Reproduction

Definition of Biology

• Biology is the scientific study of life and living things.

Properties of Life

• Order at both microscopic and macroscopic levels is a property of all life.
• Reproduction capability is a key property.
• Response to the environment via stimulus enables survival.
• Energy processing refers to how organisms obtain and use food.
• Growth, development, and aging are inherent processes.
• Adaptation to the environment occurs through natural selection.
• Sharing of DNA passes genetic information.
• Requirement of water is essential for all living organisms.

Plant Cells

• Xylem cells are thick-walled and transport water and inorganic nutrients in one direction (upwards).
• Phloem cells are thin-walled and transport water and organic nutrients in both directions (up and down).
• Storage for starch occurs in plant cells outside the transport tissues.

Reproduction Types

• Sexual reproduction involves two parents (male and female) to form a new organism.
• Asexual reproduction uses all or part of one organism to create a new one, without genetic exchange.

Energy Processing

• Autotrophic organisms (producers) create food from sunlight and other elements.
• Heterotrophic organisms (consumers) obtain energy by consuming other organisms.
• Photosynthesis requires light, carbon dioxide, and water, producing glucose and oxygen.
• Glucose is a form of sugar which equals energy in form of ATP
• Photosynthesis occurs in chloroplasts.
• Cellular respiration occurs in mitochondria.

Anabolism, Catabolism, Metabolism

• Anabolism involves constructing complex substances from simpler ones.
• Catabolism involves breaking down complex substances into simpler ones (e.g., digestion).
• Metabolism combines sun and chemical reactions to power the human body.

DNA and RNA

• DNA is genetic material, resembling a ladder with genes as its elements.
• RNA is also genetic material.

Levels of Organization

• From simplest to most complex: atoms, molecules, macromolecules (carbohydrates, lipids, proteins, nucleic acids), organelles, cells, tissues, organs, organ systems, organism.
• Tissues: collections of cells with similar functions (nervous, muscle, epithelium, connective).

Correlation of Structure and Function

• Structure and function correlate to optimize processes (e.g., leaf shape for light capture, folds in mitochondria for ATP production).

Ecological Levels

• Organisms form populations, which form communities, which form ecosystems with biotic (living) and abiotic (non-living) factors such as air, water, and soil.

Domains of Life

• Bacteria: Microscopic organisms living on the skin.
• Archaea: Microscopic organisms thriving in extreme environements.
• Eukarya: Includes multicellular kingdoms: Plantae, Fungi, Animalia, and Protists.

Protists

• Protists are subdivided into 12 kingdoms and are mostly aquatic.

Continuity of Life

• Life is based on DNA, a substance of genes.
• Genes are units of inheritance passed from one generation to the next.
• Evolution is how life evolves according to Charles Darwin.

Elements Essential to Life

• Elements are fundamental forms of matter.
• Essential elements for humans include hydrogen (H), calcium (Ca), potassium (K), phosphorus (P), and iron (Fe).
• Oxygen, hydrogen, carbon, and nitrogen make up 96% of the human body.
• Compounds have fixed ratios of two or more elements with unique properties.

Composition of Atoms

• Subatomic particles: neutrons (neutral), protons (positive), electrons (negative).
• Neutrons and protons form the atomic nucleus.
• Electrons form a cloud around the nucleus.
• Atomic number is the number of protons in the nucleus
• Mass number is sum of protrons and neutrons.
• Atomic mass can be approximated by the mass number.

Isotopes

• Isotopes are atoms of the same element with different numbers of neutrons.
• Radioactive isotopes “decay” and emit energy; used in medical care, e.g., PET scans.

Electron Shells and Chemical Behavior

• Outermost shell of an atom is the valence shell, the atoms are more stable when valence shells are filled with electrons
• Atoms do this by forming bonds with other atoms which is the fundemental principal behind chemical bonding.
• Shell capacities: 1st shell (2 electrons), 2nd shell (8 electrons), 3rd shell (8 electrons).
• Electrons determine the chemical behavior of atoms.

Chemical Bonds

• Covalent bonds involve sharing electrons (nonpolar: equal sharing, polar: unequal sharing).
• Ionic bonds: Transfer of electrons.
• Hydrogen bonds: Weak bonds.
• Chemical reactions: Making and breaking of chemical bonds.

Photosynthesis

• Photosynthesis requires carbon and water, producing oxygen, glucose and carbon.
• Atomic mass is double the atomic number.
• Cells are 70–95% water.

Organic Chemistry

• Organic chemistry studies compounds containing carbon.
• Carbon partners primarily with hydrogen, oxygen, and nitrogen.
• Hydrocarbons: chains of hydrogen and carbon with different chemical behaviors.
• Carbon can be paired with 4 atoms and is the element of life.

Water

• Water surrounds most cells.
• Water is found inside the membrane of the cell in the cytoplasm.
• Water is a polar molecule.
• Water molecules form hydrogen bonds.

Properties of Water

• Cohesion: water is "sticky" and sticks to water.
• Adhesion: water attracts to other substances.
• Transportation of water occurs through cohesion and adhesion.
• Ice floats because hydrogen bonds are more ordered, making ice less dense.

Aqueous Solutions

• Solution: liquid mixed with a substance.
• Solvent: dissolving agent.
• Solute: substance being dissolved (e.g., sugar, salt).

Hydrophilic vs Hydrophobic

• Hydrophilic substances mix well with water.
• Hydrophobic substances do not mix well with water (e.g., wax).

Acids and Bases (pH)

• pH scale describes acidity or basicity.
• pH > 7 is basic, pH < 7 is acidic.
• Human blood is neutral with a pH of 7.4.
• Pure water has equal amounts of hydrogen and hydroxide ions with body fluids having a pH between 6-8.
• Acid precipitation has a pH lower than 5.6.

Organic Molecules & Biochemistry

• Organic chemistry studies molecules that make up life which are based on carbon.

Macromolecules

• Proteins (amino acids)
• Carbohydrates
• Lipids
• Nucleic acids

Proteins

• They have a range of functions
• Keratin and collagen are proteins in the hair, bones, and skin.
• Hemoglobin transports oxygen.
• Enzymes speed up biological reactions (i.e. digestion and amylase).

Amino Acids

• Amino acids have amino and a carboxyl group, having unique side chains that give special chemical properties.
• Only 11 amino acids are synthesized by the human body; 9 are essential and must be ingested

Lipids

• Fats are made of constructed from 2 types of smaller molecules called triacylglycerides.
• Phospholipids make up animal and plant plasma membranes, only having 2 fatty acids but have a phosphor lipid instead of the 3rd.
• Steriods
• Unsaturated fats are loosened by double bonds by deep frying
• A protein known as hydrogenation can convert a cis fat from it's bent "cis” form to a straightened "trans" form

Carbohydrates

• Major types of macromolecules are based on carbon
• Cellulose is found in plants, and polysaccharides are stored as glycogen

Fats

• Saturated only have single bonds (straight)
• Functions: energy storage, insulation, and protection of internal organs like the kidneys
• Stored int he body as "adipose” tissue

Cell Theory

• All living things are composed of one or more cells.
• All plants are made of cells
• All animals are cells.
• All cells come from cells.
• All cell ar fundamental ad functional units of life

Microscope

• Anton van Leeuwenhoek invented and used microscopes to look at blood cells, skin cells and sperm.
• Robert Hooke first looke d at a tree and used the term "Cell"

Light Compounding Microscope Features

• Image reversal – up, down, left, right is the image reversal
• Magnification - up to 10x, scanning objective 4x (40x), 10x objective which is ocular, medium objective and ocular lens power will magnify 100X
• Resolving power- the ability to see great detail

Electon Microscopes

• Use beams of light
• Magnification up to 100,000 times and has a greater resolving power
• Cannot be used to observe LIVE organisms

Electron Microscope Types

• Scanning Electron Microscope (SEM) - study the surface of the cell (3D surface of a cells)
• Transmission Electron Microscope (SEM) - study inisde of the cell

Cell Theory

• Very tiny (10,000 of them can fit on the head of a pin).
• The human body has over 10 trillion cells.

Major Cell Organelles

• Nucleus - carry genes (DNA)
• Central vacuole – stores water and waste
• Endoplasmicreylicium – stores lipids and calciums (smooth) and is rough
• Golgi body - shipping and receiving center of the proteins of the cells
• Lysosoms - function are the digestive systems of your body this is at the level of the cell

Cell Types

• Prokaryotic cells: Bacteria without a membrane-bound organelle around the cells but still carry DNA.
• Eukaryotic cells: - plant and animal cells- have membrane-bound cells built inside, carry DNA

DNA and RNA

• Dna - deoxyribonucleic acid
• Rna - ribonucleic acid
• Dna can exist in 2 forms: Chromatin (thread-like), Chrososomes (coiled up)
• Dna - nucleic acid, found in all living things and it's genetic material, nucleotide – has a nitrogenous bases
• Adenine - thymine
• Guanine - cytosine

RNA

• Nucleotide polymers- made up of nucleotides and linked by the OH group on the 3' carbon of one nucleotide and the phosphate on the 5' carbon on the next
• A complimentary strands (A-T and C-G) and hydrogen bonds.
• DNA double helix consists of antiparallel nucleotide strands.

DNA Structure

• Helical in shape
• Discovered Rosalind Franklin, James Watson and Francis Crick
• RNA- type of nucleic acid, it is helical but single stranded in comparison to DNA together with ribosomes it makes proteins

RNA Types

• Mrna
• Trna
• Rrna

Explore introductory biology topics, including the definition and properties of life. Learn about plant cells and the functions of xylem and phloem, in addition to the different modes of reproduction. Understand the core concepts of biology, from microscopic order to organismal adaptation.