Biology Exam Review

Biology The study of life

Characteristics of Living Organisms Made of cell(s) Displays organization Grows and develops Reproduces Responds to stimuli Requires energy Maintains homeostasis Adaptations evolve over time

Scientific Method Ask a question or make an observation Form a hypothesis Conduct an experiment Collect and analyze data Draw a conclusion

Ecology The study of how organisms interact with one another and with the nonliving part of the environment

Levels of Organization Organism Population Community Ecosystem Biome Biosphere

Symbiotic Relationships Parasitism – one species benefits the other is harmed in some way Mutualism – both species benefit Commensalism – one species benefits the other is neither harmed nor helped

Autotrophs or Producers Collect energy from sunlight to produce food

Heterotrophs These organisms get energy by consuming other organisms

What do organisms eat? Herbivores eat producers. Carnivores prey on herbivores. Omnivores eat both plants and animals

Food Chain and Food Web A food chain is a simple model that shows how energy flows through an ecosystem. A food web is an interconnected group of food chains.

Biogeochemical Cycle A cycle that involves moving a substance (water, carbon, nitrogen…) from the living environment to the nonliving and back again

Density-dependent vs. Density-independent factors Density-dependent factors are factors that depend on the number of members in a population. Density-independent factors are factors that do not depend on the number of members in a population.

Macromolecules Carbohydrates – monosaccaharides Proteins – amino acids Nucleic acids – nucleotides Lipids – glycerol and 3 fatty acids

Cell The basic unit of life

Cell Theory All living organisms are composed of one or more cells Cells are the basic unit of structure and organization of all living organisms Cells arise only from preexisting cells

Prokaryotic vs. Eukaryotic Prokaryotic cells lack a nucleus and other membrane-bound organelles. Eukaryotic cells have a nucleus and other membrane-bound organelles.

Cell Membrane Selectively permeable Made of a phospholipid bilayer Fluid mosaic model – the phospholipids create a “sea” in which the other molecules can float

Cytoplasm Semifluid material in which organelles are found in a eukaryotic cell This is where all prokaryotic cell activities occur

Nucleus Contains the majority of the cell’s DNA Surrounded by nuclear envelope Where chromosomes are located

Ribosomes The organelle that helps manufacture proteins Made by the nucleolus Can be free-floating or attached to the ER

Endoplasmic reticulum (ER) Membrane system of folded sacs and interconnected channels Rough ER or Smooth ER Synthesizes proteins, lipids and carbohydrates

Lysosome Digestive body of the cell

Centrioles Found in animal cells and are used for structure during cell division

Mitochondria Converts glucose into ATP Site of cellular respiration Referred to as “powerhouses” of cell

Chloroplasts Found in plant cells but not animal cells Site of photosynthesis

Cell Wall Thick, rigid, mesh of fibers that provides protection and support to cells Found in plants but not animals

Diffusion and Osmosis When a substance moves from an area of high concentration to low (DIFFUSION) Diffusion of water (OSMOSIS)

Facilitated Diffusion Diffusion with the assistance of transport proteins

Cell Cycle Interphase – preparation for nuclear division Mitosis – division of the nucleus Cytokinesis – division of the cytoplasm

Interphase Gap 1 Synthesis Gap 2

Mitosis Prophase Metaphase Anaphase Telophase

Cancer The uncontrolled growth and division of cells Substances known to cause cancer are called carcinogens

Haploid vs. Diploid Haploid – n - gametes Diploid – 2n – body cells

Meiosis Production of gametes, or sex cells Often called reduction division RECALL – Crossing-over occurs during prophase I of meiosis

Genetics Branch of biology focusing on heredity

Homozygous Contains two of the same alleles AA, aa

Heterozygous This is when an organism has two different alleles Aa, Yy

Genotype vs. Phenotype The genotype is the organism’s allele pairs. The phenotype is the physical appearance or outward expression of an allele pair.

Carrier An individual who is heterozygous for a recessive disorder and shows no symptoms of the disorder

Examples of autosomal recessive disorders Cystic fibrosis Albinism Galactosemia Tay-Sachs disease

Examples of Dominant Disorders Huntington’s disease Achondroplasia

Sex-linked Recessive Disorders Red-green colorblindness Hemophilia

Pedigree A diagram that traces the inheritance of a particular trait through several generations

Incomplete Dominance The heterozygous phenotype is in between the two homozygous phenotypes A pink flowered snapdragon is produced from parents in which one had red flowers and one had white flowers.

Codominance This is when both alleles are expressed at the same time. Roan horse – both red hair and white hair

Sex-linked Traits Traits controlled by genes located on the X chromosome Since males have only one X chromosome, they are affected by sex-linked recessive more often than females.

Nucleotide 5-carbon sugar Phosphate Nitrogenous base

DNA Deoxyribonucleic acid Double helix Five-carbon sugar - deoxyribose Bases: adenine, thymine, guanine, cytosine

Chargaff’s Rule Adenine pairs with thymine Guaning pairs with cytosine

RNA Ribonucleic acid Generally a single-strand Five-carbon sugar is ribose Bases: adenine, uracil, guanine, cytosine

Three Major Types of RNA Messenger RNA (mRNA) – travel from nucleus to cytoplasm and direct the synthesis of proteins Ribosomal RNA (rRNA) – associate with proteins to form ribosomes Transfer RNA (tRNA) – transport amino acids to the ribosome

Semiconservative Replication Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental strand and one new DNA strand.

Three Main Stages of Replication Unwinding – DNA helicase Base pairing – DNA polymerase Joining – DNA ligase

Transcription Synthesis of RNA

Translation The code is read and converted to make a protein

Evolution Cumulative changes in groups of organisms through time