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SCIENCE GATEWAY

This review covers topics such as the cell theory, cell parts and their functions, cell reproduction, genetics, and DNA structure. It is designed to be used with individual sections from the Gateway Review Manual.

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SCIENCE GATEWAY

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  1. SCIENCE GATEWAY REVIEW AND PRACTICE BIOLOGY

  2. TOPICS FOR REVIWFor use with individual sections from Gateway Review Manual • The Cell Theory - Mitosis and Meiosis • Genetics and DNA • Energy/ Matter Transformations - Respiration and Photosynthesis • Adaptation • Life Functions

  3. #1 CELL THEORY

  4. STATES THE FOLLOWING: All organisms are made up of cells. The cell is the basic living unit of life New cells only come form other living cells. CELL THEORY

  5. NUCLEUS The brain of the cell; contains DNA; controls cell division and growth. PARTS OF A CELL • CHROMOSOMES • Dictate cell functions; contain genes; coordinate cell activities • Fluid between nucleus and cell membrane; contains ribosomes • CYTOPLASM

  6. Location of protein synthesis PARTS OF A CELL (con.) • Protects cell and controls all movement • in and out of cell. CELL MEMBRANE • Series of canals within cytoplasm; • contain ribosomes • (smooth and (rough) • ER • (endoplasmic reticulum) • RIBOSOME

  7. GOLGI APPARATUS MITOCHONDRIA Acts like a warehouse where proteins are processed and shipped to all parts of the cell. Cell parts that produce energy from digested food. PARTS OF A CELL

  8. NUCLEOLUS CENTRIOLE VACUOLE Surrounds the nucleus and separates it from the rest of the cell. Cell part that helps with reproduction. Liquid storage area for minerals, food and water PARTS OF A CELL

  9. CHLOROPLASTS CELL WALL Green structures involved in making food; used for photosynthesis Located outside cell membrane; gives support to cell. PLANT CELLS:DIFFERENCES

  10. CELL REPRODUCTIONMitosis vs. Meiosis • Processes by which cells are reproduced. • Both processes end up with more cells. • Both involve multiple phases.

  11. Produces body cells (somatic) Diploid daughter cells Produce 2 daughter cells In metaphase, chromosomes line up singley 1 nuclear division Produce cells for growth and repair Daughter cells have 2 sets of chromosomes (pairs) Daughter cells genetically identical to parent cell Daughter cells genetically identical Mitosis

  12. 1-Prophase nuclear membrane disappears centrioles pull apart fibers of protein form 2- Metaphase centrioles move to opposite ends of cell pairs of chromatids are pulled toward center 4 pairs of sister chromatids line up in the center Phases (steps) of Mitosis

  13. 3-Anaphase sister chromatids pulled apart by fibers each chromatid strand is pulled toward ends of cell. (each one is an exact copy of one original chromosome) 4-Telophase complete set of chromosomes at each end of cell fibers disappear nuclear membrane starts to form cell membrane pinches in until cytoplasm divides in half and 2 new cells have formed Phases (steps) of Mitosis (con.)

  14. Produces sex cells (gametes) Haploid daughter cells 4 daughter cells produced In metaphase I, chromosomes line up as homologous pairs (synapsis); 2 double chromosomes line up side by side; crossing over occurs 2 nuclear divisions Produce cells for sexual reproduction Daughter cells have only 1 member of each pair of chromosomes; only ½ the genes from the parent cell Genetic diversity through crossing over and random separation of chromosome pairs. Meiosis

  15. 1-Prophase sister chromatids shorten and thicken nuclear membrane starts to break down centrioles move apart and fibers are formed matching chromosomes form pairs 2-Metaphase centrioles move to opposite ends sister chomatids attach to fibers 2 pairs of matching chromosomes move to center of cell Phases (steps) of Meiosis

  16. 3-Anaphase matching chromosomes part cytoplasm divides in half 4-Telophase 2 new cells - each has 2 chromosomes centrioles double and form fibers again no new nuclear membrane yet Phases (steps) of meiosis (con.)

  17. 5-Second division begins and occurs in both of the new cells centrioles move apart and form fibers sister chromatids move to center of each cell 6-Second division continues sister chromatids part and move to ends of cell nuclear membrane reforms around each new set of chromosomes cytoplasm divides and 4 new sex cells form Phases (steps) of Meiosis (con.)

  18. #2 GENETICS AND DNA

  19. GENETICS AND DNA • Genetics is the study of how traits are passed from parent to offspring. • Genes - sections of the chromosomes found in cells; control these traits. • DNA is a molecule located on a chromosome that makes up genes and determines traits of all living things.

  20. BODY CELLS make up most of the body’s tissues and organs 2 of each chromosome for a total of 46 SEX CELLS can be a sperm cell (male) or an egg cell (female) only 1 kind of each chromosome; half as many as chromosomes in body cells CHROMOSOMES - located in nucleus; split and produce new cells; contain genes

  21. STRUCTURE of DNA • Holds information needed for cell function and carries information needed to make proteins • Model looks like a ladder in a twisted shape • DNA backbone (or sides) are made up of alternating sugars and phosphates. • “Rungs” of the ladder are composed of 4 nitrogen bases (adenine, thymine, cytosine, guanine) which are joined together in a specific order (via a covalent bond which is very strong).

  22. STRUCTURE of DNA (con.) • This order is based on our genetic history, and makes up our genetic characteristics (eye, hair color; ear shape and size, etc.) • These 4 bases form a “code” which spells out a certain “message”. • This code is similar to ‘code’ of 26 letters in our alphabet-(a combination of letters to form words)

  23. DNA STRAND • A ALWAYS pairs up with T; C ALWAYS pairs up with G: A-T; C-G S-P-S-P-S-P-S-P G A C T C T G A S-P-S-P-S-P-S-P

  24. The making of RNA • RNA is formed from DNA: The strands split at the (weak) hydrogen bonds where needed to make mRNA. (messenger RNA) • The thymine (T) in DNA is replaced with uracil (U). • This process takes place in the ribosomes within a cell. • Process is referred to as transcription.

  25. TRANSLATION:language of amino acids – creation of a protein • mRNA is the blueprint that tells the order of amino acids • mRNA is the CODE composed of a single strand of nucleotides (A,U,C,G) • Nucleotides divided into patterns of 3 letters in a row – (triplet codon) = 1 amino acid • Each codon forms long chain to produce proteins. • STOP codons (UAA, UAG, UGA) tell ribosomes when to stop making a proteins

  26. #3 - ENERGY/MATTER TRANSFORMATIONS RESPIRATION AND PHOTOSYNTHESIS

  27. RESPIRATION -Used by plants and animals to get energy from food -Energy stored in sugars (glucose) and other food is released when organisms break down food into smaller molecules and combine with oxygen -Takes place in cell cytoplasm (in mitochondria) -After breakdown of sugar, waste products of CO2 and water leave through cell membrane.

  28. RESPIRATION(con.) -Chemical reactions produce nucleotide, ATP which stores energy and then releases it when needed -ATP is important part of cells; can make materials needed for life functions.

  29. PHOTOSYNTHESIS • Process of producing food in plants • Chloroplasts (cells) use energy from sun to produce glucose. • CO2and water are also used; oxygen is given off as waste.

  30. Light Reaction Chlorophyll traps energy in sunlight. ATP is produced ATP can store energy for cell processes. Water is split into H and O Some O is used in respiration; much is given off in air. Dark Reaction CO2 and other chemicals combine to form sugar (energy to do this comes from ATP). Some of sugar produced is used in respiration; some for growth. Extra sugar stored in roots, stems and leaves. PHOTOSYNTHESIS (con.)

  31. RELATIONSHIP BETWEENPHOTOSYNTHESIS AND RESPIRATION • ALL plants carry on respiration • Plants with chlorophyll carry on photosynthesis. • Processes depend on each other • Oxygen released in P is used in R. • Water and CO2 in R are used in P.

  32. #4 ADAPTATIONRELATIONSHIPS IN NATURE

  33. ADAPTATION • Symbiosis • Feeding relationships with an ecosystem • How cooperation and competition exist in nature.

  34. -A trait that makes a living thing able to survive in its surroundings. -Controlled by genes Examples: Web feet on a duck to help it swim White fur on a polar bear to help it blend in to the snow Extra fur on an animal to survive the cold Scent of a skunk to ward off enemies ADAPTATION

  35. NATURAL SELECTION • - Process by which something in a living thing’s surroundings determines if it will survive in order to reproduce offspring. • Something in nature does the selecting. • Living things that are suited to their surroundings are the ones who will most likely survive and reproduce.

  36. SYMBIOSIS- Relationship between species living in direct contact with each other; exchange of benefits • PARASITISM- One species benefits; other is harmed • ex: food/shelter in exchange for decrease in warmth and reproduction. • Fleas on a dog / bacteria or virus in your body • MUTUALISM- Both species benefit from each other. Termites on a dead log / bacteria in intestine provides body with vitamin B12 - human provides home for bacteria • COMMENSALISM- One species benefits; the other is unaffected. • ex: sea anemone provides food and shelter; fish provides nothing

  37. COMMUNITIES • An area full of different species of living things, all dependent on one another for survival • Habitat – place where an organism lives • Niche – an organism’s job within a community. • Types of organisms: producer – consumer decomposer

  38. FEEDING RELATIONSHIPSwithin an ecosystem • Ecosystem is composed of varieties of food webs, made up of various food chains. • Each chain consists of producers, consumers and decomposers. • Example producer – green plants (receive nutrients from soil) consumer –primary (animals who eat plants) or secondary (animals who eat other animals) decomposer – bacteria (from living waste material; makes soil fertile)

  39. FOOD CHAIN • PRODUCER • Produces food for themselves and other living organisms using energy from the sun • CONSUMER • PRIMARY – eats plants • SECONDARY – eats other animals • DECOMPOSER • Breaks down food and recycles it for nature

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