Topics that Always Important
What are the 4 major macromolecules? Recognize their monomers and polymers
Macromolecules: Carbohydrates, proteins, lipids, nucleic acid
Monomers: monosaccharides, amino acids, fatty acid and glycerol, nitrogenous base + five carbon sugar + phosphate group
Polymers: polysaccharides, polypeptide bond, fats or lipids, RNA or DNA
General characteristics of enzymes
Enzymes: proteins that lower the activation energy required and allow reactions to happen at the normal temperature of cells. Specific: only work on one particular reaction. Reusable: used over and over again for that reaction. Named after their substrate (the reactant that the enzyme helps.) Substrate binds to enzyme at the active sight.
How to think like a scientist J
Photosynthesis & Plant Structure (4)
What is the equation for photosynthesis?
6CO2 + 6H2O + energy of sunlight = C6H12O6 + 6O2
How does this process relate to cell respiration?
The products of cells respiration are the reactants for photosynthesis and the products of photosynthesis are the reactants or cell respiration.
What are the major reactants and products of photosynthesis? When/where are each taken in or given off during the overall light and dark reactions of photosynthesis?
Reactants: Carbon dioxide (Calvin cycle. From atmosphere), water (light reactions. From atmosphere. Split to replace electrons and release hydrogen that adds to the gradient.), sunlight (light reactions. Pigments in thylakoids absorb light)
Products: Glucose (Calvin cycle. Formed from carbon dioxide), oxygen (Light reaction byproduct from splitting of water molecules)
ATP and NADPH are formed in the light reactions and used in the Calvin Cycle.
How are light reactions and Calvin cycle related?
The light dependent reactions produce NADPH and ATP. They are used in the Calvin Cycle to produce glucose.
Why are plants green?
Plants contain chlorophyll a and b. They absorb violet-blue and orange-red. They reflect green which is what gives plants there green color.
Location of photosynthetic processes within a plant cell
Chloroplasts
Light Dependent: Thylakoid membrane
Calvin Cycle (light independent): stroma
Identify structure and function of a plant leaf in cross section
What is the function of stomata?
Stomata allow the exchange of carbon dioxide and oxygen (needed for photosynthesis and respiration) between the internal tissues of the plant and the outside atmosphere. They are also the main route by which water is lost from the plant (water vapor), and they can be closed to conserve water, the movements being controlled by changes in turgidity of the guard cells. At night the stomata may allow oxygen to diffuse in and carbon dioxide out because only respiration is taking place. However in many plants the stomata close at night, preventing this gas exchange.
Mitosis (8)
What function does cell division serve?
Allows organisms to grow larger and replace damaged or dead cells. When a cell no longer has enough surface area to support its volume, the cell must divide.
What are the major events of: G1, S, G2, M phases?
G1: preparation for synthesis, normal cell functions, synthesis of RNA or other macromolecules.
S: replication of DNA
G2: preparation for mitosis
M: prophase: Nuclear membrane breaks down, Chromosomes condense, Microtubules from the mitotic spindles, Centrioles move to opposite sides of the cell (plants DO NOT have centrioles- the centrosome is used instead), The microtubules connect the kinetochore of each sister chromatid to the spindle poles around each centriole
Metaphase: Spindles move chromosomes to the metaphase plate, perpendicular to the poles down the center of the cell
Anaphase: Enzymes break down the connection of the sister chromatids at the centromere, Sister chromatids are pulled apart to opposite ends of the cell, Sister chromatids are now called Chromosomes
Telephase: Chromosomes begin to expand, Nuclear envelope reappears making two nuclei
Draw a cell with 4 chromosomes as it progresses through G1, S, G2, and all the phases of mitosis.
G1 S G2 Prophase Metaphase Anaphase Telophase
Describe the formation and function of spindle fibers.
Form from the centriole, specifically the microtubules that are the centriole
Function: Attach to the kintechore and pulls apart the sister chromatids to opposite sides of the cell
What is cytokinesis, centromeres, centrioles, chromatids?
Cytokinesis: divides the cell in two. In animals, the plasma membrane pinches in forming a cleavage furrow until the cell completely pinches apart into two separate cells. In plants, cell plate forms down center of cell and ultimately forms two separate cells.
Centromeres: where the two sister chromatids are attached
Centrioles: A minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division
Chromatid: One of the usually paired and parallel strands of a duplicated chromosome, joined by a single centromere.
Meiosis (12)
Understand haploid versus diploid
Haploid: set, 23 unique chromosomes, “n”, gametes
Diploid: 2 sets, 46 chromosomes and 23 pairs, “2n”, homologues, somatic regular body cells
Differentiate between asexual and sexual reproduction. How are they evident in animals and plants?
Asexual: one parent, offspring are genetically identical
Sexual: two parents, offspring are genetically different
Simple organisms reproduce asexually; most animals and plants reproduce sexually
What are Mendel’s Laws and how do they relate to meiosis?
Law of segregation: When the F1 generations were self-pollinated, the recessive trait reappeared. For each trait an individual has two alleles (one from each parent). In turn, each individual can only pass one or the other of its alleles to its offspring.
Law of independent assortment: The inheritance of one gene does not influence the inheritance of another. In meiosis, the chromosomes line up randomly on the equator to be separated. If your parents are heterozygous for any traits, this leads to lots of possibilities!
What are homologous chromosomes and sister chromatids?
Homologous Chromosomes: pairs of similar chromosomes. Similar in size, structure, and carry genes for the same traits but may have different alleles. Each member of a pair comes from each parent.
Sister chromatids: One of the usually paired and parallel strands of a duplicated chromosome, joined by a single centromere. Identical copies of the same chromosome
Reproduction & Development (10 – 12)
Plants
Sketch a flower and identify (1) carpel (2) stigma (3) anther (4) stamen (5) sepals (6) ovule & ovary (7) petals (8) style. What are the functions of these parts?
Describe the functions of phloem, xylem, ground and meristematic tissue
Phloem: transports food (sugars made)
Xylem: transports water
Ground tissue: fills plant’s body, gives shape and internal support
Meristematic tissue: source of new growth for the entire life of the plant
What is pollination? What is fertilization? What is the endosperm?
Pollination: Anther sheds pollen, Lands on stigma, Pollen germinates and forms a pollen tube, Tube grows down towards ovule, carrying two sperm nuclei. Double Fertilization, One sperm nucleus fuses with egg, Other sperm nucleus fuses with polar nuclei à triploid cell that develops into endosperm
Fertilization: union of sperm and egg
Endosperm: Transfers nutrients from mother plant to embryo. Some species – completely digested by embryo, others… endosperm persists as nutrient source for young plant until photosynthesis begins.
Where does fruit come from? What is the selective advantage of fruits?
Fruit comes from a mature ovule. Fruits grow when the conditions are best for their survival.
What is germination? How does it proceed?
Germination: the process whereby seeds or spores sprout and begin to grow
Proceeding: Mitosis in zygote forms mass of cells (embryo), Endosperm forms: Transfers nutrients from mother plant to embryo. Some species – completely digested by embryo, others… endosperm persists as nutrient source for young plant until photosynthesis begins. Differentiation begins: small bumps form on embryo (cotyledons). Elongation: Quick cell division elongates embryo. New cells differentiate into specialized structures. Seed Coat: Maternal flower tissue encloses endosperm & embryo. Embryo stops growing (dormant.) No enzyme activity, No transcription or translation, Very slow, little cell respiration. Waits for optimal conditions to sprout.
Process:
1. Good water, oxygen temperature
2. Embryo resumes metabolism, growth, development
3. Enzymes made – digest food in endosperm & cotyledons à goes to growing areas of embryo
4. Respiration ramps up
5. Water restores turgor pressure to embryo cells
6. Embryo cells swell & grow
7. Seed coat ruptures
8. Embryonic root emerges
9. Shoot grows up through soil
Animals
Explain major differences between internal fertilization and external fertilization.
External: simple aquatic animals, gametes released into water, no guarantee of fertilization, no protection for zygote
Internal: male ejaculates sperm into female, fertilization inside female body, gametes protected, increased likelihood of fertilization, requires fewer gametes, zygote protected inside female body
Differentiate between morula, blastula, gastrula, neurula.
Morula: 16 cells to 64 cells
Blastula: at the end of cleavage, all cells are same size and appearance, usually hollow, shape depends on structure and arrangement of the egg and yolk
Gastrula: after differentiation and morphogenesis. Forms primary germ layers
Neurula: The stage of a vertebrate embryo when gastrulation is largely finished and a neural plate is forming, ending with formation of the neural tube.
What happens in cleavage? Morphogenesis? Gastrulation?
Cleavage: division, immediately after fertilization
Morphogenesis: process of differentiation
Gastrulation: form primary germ layers: ectoderm, mesoderm, endoderm
Identify the location of the primary germ layers and what tissues they give rise to.
Ectoderm: outer layer, will form skin, nervous system and related structures
Mesoderm: middle layer, will form bone, muscles, heart, blood
Endoderm: inner layer, “tube like”, will form lining of digestive system
Compare and contrast a sperm cell with an egg cell.
Sperm: mobile, smaller, nucleus, flagella, mitochondria, not stored food so it cannot survive for long
Egg: Large, immobile, nutrient storehouse, can survive longer
What is the function of fertilization? How do we know when it has been completed?
The function is to reproduce. HCG is released and the woman’s menstrual cycle stops
How are molecules exchanged during mammalian development?
The placenta: forms in gastrulation, chorion forms villi into uterine lining.
Genetics (13)
Understand the role of probability in genetics. Can you predict events involving: coins? cards?
Mendelian inheritance reflects the rules of probability. Rule of multiplication “and”: chance that two or more independent events occur simultaneously.
Rule of addition “or”: chance of an event that can occur in two or more different ways
What is the likelihood of having a boy? What is the likelihood of multiple children with the same disorder if given the genetic background of the mom and dad?
50% chance. Need to know the genetic background. Would use rule of multiplication
How are new combinations of alleles generated through crossing-over, sexual reproduction, and mutation?
Crossing over: The exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring
Sexual reproduction: Homologous chromosomes line up randomly during meiosis so each sperm and egg receive a random set of chromosomes
Mutation: one allele is directly changed to another
What is nondisjunction? What can it cause? How is that related to Down Syndrome?
Nondisjuction: homologous chromosomes fail to separate during meiosis
The spindle fibers do not work properly
Down syndrome is where there is an extra 21st chromosome
Compare and contrast genotype with phenotype.
Genotype: genetic makeup, what alleles you have
Phenotype: what you look like, what alleles are expressed
What does it mean to be heterozygous? Homozygous? Dominant? Recessive? A carrier? A hybrid?
Heterozygous: has two different alleles. One dominant and one recessive
Homozygous: has two of the same alleles
Dominant: allele that is expressed most of the time. If heterozygous, dominant allele is expressed
Recessive: allele that is expressed less of the time. Only expressed when homozygous recessive
Carrier: Has one normal allele and one defective allele.
Hybrid: Of mixed character; composed of mixed parts
Describe the following modes of inheritance – incomplete dominance, multiple alleles, codominance, sex-linked traits. How they work genetically, and how they affect phenotype.
Incomplete dominance: neither allele is dominant or recessive. if RR and WW are mixed you get RW. RR (red) and WW (white) = RW (pink)
Multiple alleles: More than two alleles code for one trait. C-full color, dominates over Cch, Ch, c, Cch – chinchilla, dominates over Ch and c, Ch- himalayan, dominates over c, c- albino, recessive to all
Codominance: Both alleles are dominant, neither is recessive. B=black, W=white. BB=black, WW=white, BW=black and white
Sex-linked traits: Trait can be dominant or recessive, Probability of inheritance is altered because the trait is on the X chromosome. Female with XX1 and male with XY gives offspring with XX, XX1, XY, and X1Y. One normal female, one normal male, one carrier female, and one defected male
How is the sex of offspring determined?
It depends if the father gives an X or Y chromosome
Blood types – genetic basis, inheritance, compatibilities
Blood types: A, B, O, AB. Multiple alleles, Polygenic and Codominance! Multiple alleles- A, B, O. Polygenic- one gene controls type, another gene controls rH factor (+, -). Codominance- A and B are codominant but both dominate over O. Inherit one allele from each parent. AB is the universal recipient and O is the universal donor. A can receive from A or O. B can receive from B or O. AB can receive from A, B, AB, or O. O can receive from O.
Monohybrid & dihybrid crosses. Genetic problem solving.
Pedigree analysis.