Biology Chapter 7-11 (copy)

Photosynthesis converts solar energy and carbon dioxide into chemical energy of carbohydrates

Autotrophs; make their own food (carbohydrates); includes plants, algae, cyanobacteria;

Photosynthesizers make their own food; animals eat them to get their food; those animals are called heterotrophs; they get carbon and energy by breaking down organic molecules of other organisms

Plant leaf; upper and lower epidermis; lower epidermis has openings called stomata (plural; stoma singular); stomata allow carbon dioxide in; allow water and oxygen out; middle layer is mesophyll;

Chloroplasts; site of photosynthesis; found in mesophyll cells of plant leaf; fluid filled interior is called stroma; flattened sacs called thylakoids; thylakoid membrane contains chlorophyll and other pigments that are capable of absorbing solar energy;

Oxidation; molecule loses electrons; in cells, oxidation is loss of hydrogen atom

Reduction; molecule gains electrons; in cells, reduction is gain of hydrogen atom

Redox reaction; one molecule oxidized, another reduced; transfer of electrons from one molecule to another;

Light reactions; occur only when sun is out; solar energy energizes electrons, which move down an electron transport chain; energized electrons taken up by NADP+, which is reduced to NADPH;

Photosystem I and II are in thylakoid membrane; each contains a pigment complex that absorbs solar energy and an electron-acceptor molecule;

Solar energy excites electrons in photosystem II pigment complex; these electrons are energized, leave the complex, and are captured by electron-acceptor molecule; pigment complex replaces electrons by splitting a water molecule and capturing hydrogen; oxygen given off as waste;

Excited electrons are passed down electron transport chain (series of molecules that pass electrons from one molecule to the next, to the next, etc also in thylakoid membrane)

Electrons eventually end up at photosystem I which has lost electrons when its pigment complex absorbed solar energy; excited electrons from photosystem I go to electron-acceptor molecule and then down another electron transport chain; electrons eventually captured by NADP+ to form NADPH; this is major product of light reactions;

Calvin cycle; a series of reactions that produces carbohydrates before returning to the starting point; does not require light; uses products of light reactions to reduce carbon dioxide from atmosphere;

                Carbon fixation; carbon dioxide (CO2) from atmosphere combined with RuBP to form six carbon molecule;

                Carbon dioxide reduction; several steps needed to convert six carbon molecule into glyceraldehye 3-phosphate (G3P); NADPH from light reactions used in these steps; for every 6 G3P produced, 1 used by plant for its needs;

                RuBP regeneration; several steps needed to convert 5 G3Ps back into RuBP;

Plant can use G3P to make just about any organic molecule it needs (figure 7.13, page 125); can make glucose, fatty acids, amino acids; from glucose, plant can make starch, cellulose;

Most plants are C3 plants; produce stable 3 carbon molecule after CO2 fixation;

Other types of photosynthesis;

                C4 plants; produce a 4 carbon molecule after CO2 fixation; grow in hot, dry conditions; 4 carbon molecule transported to different cell for Calvin Cycle; includes sugarcane, corn, Bermuda grass

                Crassulacean-acid metabolism (CAM); grow in warm, dry conditions; also produce 4 carbon molecule after CO2 fixation; close stomata during day to prevent water loss; fix CO2 at night and carry out Calvin Cycle during day; includes desert succulent plants;

Adenosinse Triphosphate (ATP) is energy molecule of cell (chapter 6, page 99); ATP is made by adding a phosphate group onto adenosine diphosphate (ADP); most ATP is made by breaking down organic molecules and using the released energy to make ATP from ADP and phosphate; the process for doing this is cellular respiration;

Cellular respiration; the process by which cells acquire energy by breaking down nutrient molecules produced by photosynthesizers; it requires oxygen and produces CO₂ as waste (opposite of photosynthesis);

Glucose is a high-energy molecule; all chemical bonds that hold molecule together represent chemical potential energy; as molecule is broken down in cellular respiration, energy released is used to form ATP

NAD+ is an electron carrier; it will accept two electrons (reduced to NADH) and then release those electrons to another molecule (oxidized back to NAD+)

Phases of cellular respiration: glycolysis; preparatory reaction; citric acid cycle (Kreb’s cycle); electron transport chain;

Glycolysis; takes place in cell cytoplasm; does not need oxygen; glucose modified and then split into two molecules of glyceraldehyde 3-phosphate (G3P); several steps to convert each G3P into pyruvate;

Preparatory reaction; takes place in mitochondria; pyruvate converted to acetyl-CoA;

Citric Acid cycle; takes place in mitochondria matrix; acetyl CoA combines with oxaloacetate to form citrate; several steps used to convert citrate back to oxaloacetate; during these steps NAD+ is reduced to NADH;

Electron transport chain; takes place in inner membrane of mitochondria; a series of carriers that pass electrons from one to the next; NADH from citric acid cycle passes its electrons to first carrier, which passes them to next carrier, etc;

Final electron acceptor in electron transport chain is oxygen; that is why we need oxygen;

As electrons are passed, H+ is released; H+ passes through enzyme called ATP synthase and supplies energy to make ATP from ADP and phosphate; most of ATP in cellular respiration made here;

Fermentation; anaerobic process that produces a limited amount of ATP in the absence of oxygen; in animal cells, pyruvate is reduced to lactate; yeasts and some bacteria convert pyruvate to ethanol; in absence of oxygen, electron transport chain doesn’t work; this leads to citric acid cycle not working;

Metabolism; all chemical reactions that take place in cells

                Catabolism; reactions that break down big molecules into smaller ones

                Anabolism; reactions that build up big molecules from smaller ones

Metabolic pool; collection of organic molecules in cells; can be used for energy or to build big molecules (figure 8.12, page 136);

Proteins are broken down into individual amino acids; these can be broken down further and enter glycolysis or citric acid cycle if needed; humans can synthesize 11 of the 20 amino acids from other molecules; the other 9 amino acids are referred to as essential amino acids; they must be present in the food we eat;

Fatty acids can be converted into acetyl CoA and enter the citric acid cycle if needed; acetyl CoA can be used to make fatty acids if needed;

Photosynthesis vs. cellular respiration (figure 8.13, page 137)

Photosynthesis                                                                       cellular respiration

Takes in CO2                                                                            gives off CO2

Gives off oxygen                                                                     takes in oxygen

Endergonic; produces sugars                                               exergonic; breaks down sugars

Uses ATP                                                                                  produces ATP

The cell cycle (figure 9.1, page 148)

                G1; normal growth and function

                S; DNA replication

                G2; final preparation for division

                M; mitosis and cytokinesis

Cell cycle checkpoints; cell checks to see if things are normal

                G1; is DNA damaged; can it be repaired

                G2; was DNA replicated properly

                M; are chromosomes lined up properly in cell center

Apoptosis; programmed cell death; if things not normal in any of the checkpoints, the cell should die

Eukaryotic chromosome (figure 9.3, page 151)

                A chromosome is one long DNA molecule; much longer than the cell; it has to be specially folded to fit into cell nucleus;

                DNA wrapped around histone proteins

                Zigzag structure formed

                Loose coiling into radial loops to form chromatin

                Tight compaction to form inactive heterochromatin

                Further coiling to form metaphase chromosome; chromosome in metaphase has been duplicated and consists of two sister chromatids

Mitosis; cell division; organism produces more cells to replace dead cells or to grow bigger; new cells identical to original cell;

                Chromosome number; diploid number is two sets of chromosomes; present in most cells; haploid is one set of chromosomes; present in gametes (reproductive cells)

Phases of mitosis (figure 9.5, pages 154-155)

                Prophase; chromatin condenses into chromosomes; nuclear envelop fragmenting

                Metaphase; centromeres of chromosomes lined up at equator of cell

                Anaphase; sister chromatids part and move toward poles

                Telophase; chromosomes reach poles; nuclear envelope reforms

Cytokinesis; division of cell into two cells; starts in late anaphase; continues through prophase

Cancer; uncontrolled cell division; damaged cell continues to divide; can form tumor; when tumor interferes with normal tissue function, symptoms of cancer result;

                Oncogenes; code for proteins that promote cell cycle and prevent apoptosis; like gas pedal on car stuck in down position

                Tumor suppressor genes; code for proteins that inhibit cell cycle; like brake pedals on car; if not working, cell cycle doesn’t stop;

Prokaryotic cell division; binary fission (figure 9.12, page 162); DNA replication copies the chromosome; chromosome copies pulled to opposite ends of cell; cytokinesis divides cell into two cells; the two cells are identical to original cell;

Meiosis overview; the type of nuclear division that reduces the chromosome number from diploid (2n, two sets of chromosomes) to haploid (1n, one set of chromosomes);

It occurs only in the production of gametes (reproductive cells; egg and sperm in animals); gametes are haploid; sexual reproduction occurs when haploid gametes merge into a diploid cell called a zygote; zygote undergoes development to become adult;

Meiosis is necessary because the gametes must be haploid; diploid gametes would lead to the number of chromosomes in cells to double every generation;

Homologous chromosomes (homologues); chromosomes of the same size and carry genes for same traits; genes for a trait may not be identical on each member of a pair of homologues;

Allele; alternative form of a gene;

Humans have 46 chromosomes in diploid cells; made up of two sets of 23 chromosomes (inherit one set from each parent) or 23 pairs of homologues; karyotype shows picture of all the chromosomes of an individual;

Chromosomes replicated in S phase of cell cycle; results in chromosomes composed of two sister chromatids; sister chromatids attached to each other at centromere;

Genetic variation

                Crossing over; exchange of genetic material between non-sister chromatids in homologues; homologues pair up in early meiosis and parts of chromatids switch pieces; results in chromatids different than either parent chromosome;

                Independent assortment; homologue pairs separate independently in metaphase I; maternal and paternal chromosomes may be oriented toward either pole;

                Fertilization; union of male and female gametes; offspring have some characteristics of each parent and are not identical to either parent or any of their siblings;

Phases of meiosis

                Meiosis I (figure 10.5, page 172)

Prophase I; chromatin condenses into chromosomes; nuclear envelope fragments; homologues pair up; crossing over occurs

Metaphase I; homologue pairs lined up at metaphase plate in cell center;

Anaphase I; homologues separate and are pulled to opposite poles

Telophase I; chromosomes reach the poles; new nuclear envelope may form

Cytokinesis divides cell into two cells;

                Meiosis II

Prophase II; nothing specific mentioned in text; nuclear envelope will fragment

Metaphase II; chromosomes line up at metaphase plate in cell center

Anaphase II; sister chromatids separate and are pulled to opposite poles

Telophase II; chromosomes reach poles; new nuclear envelope forms

Cytokinesis; divides cells into a total of four cells;

Resulting cells develop into gametes;

Mitosis compared to meiosis (figure 10.7, page 174; tables 10.1, 10.2, page 175)

Mitosis occurs in all tissues during growth and repair; results in two identical daughter cells;

Meiosis occurs only in the formation of gametes; results in four genetically different haploid cells;

Spermatogenesis; production of sperm; primary spermatocyte undergoes meiosis I and meiosis II to produce haploid spermatids; these mature into sperm

Oogenesis; production of eggs; primary oocyte goes through meiosis I to become secondary oocyte; if fertilized, secondary oocyte goes through meiosis II to become egg;

Changes in chromosome number or structure

                Aneuploidy; more or fewer than the normal number of chromosomes; results from non-disjunction (chromosomes don’t separate properly in anaphase); most common in humans is trisomy 21; three copies of chromosome 21 instead of two copies; individual has 47 chromosomes instead of 46; this is Down syndrome;

                deletion; portion of chromosome missing

                duplication; a chromosome segment occurs more than once in the same chromosome

                inversion; chromosome segment turned around;

                translocation; crossing over between nonhomologues;

Punnett square; diagram showing possible offspring of a cross;

Mendel’s Law of Segregation

                Each individual has two factors for each trait

                The factors segregate (separate) during formation of gametes

                Each gamete contains only one factor for each pair of factors

                Fertilization gives each new individual two factors for each trait

Allele; alternative form of a gene

Homozygous; two identical alleles

Heterozygous; two different alleles

Dominant; the allele expressed in the heterozygous individual

Recessive; the allele masked (not expressed) in the heterozygous individual

Genotype; the alleles an individual receives at fertilization

Phenotype; the physical appearance of an individual

Law of independent assortment

                Each pair of factors segregates (assorts) independently of the other pairs

                All possible combinations of factors can occur in the gametes

Dihybrid cross; tracking two traits at the same time

Mendel looked at several traits one at a time; recognized patterns in some; cross two phenotypes; first generation showed only one phenotype; second generation showed both phenotypes in 3:1 ratio; ratio resulted from crossing two heterozygous individuals;

Pedigrees; diagram showing inheritance in a family; usually multiple generations;

                Square represents male;

                Circle represents female;

                Shaded figure shows individual with trait being traced

                Line between two represents mating

                Children connected to parents by horizontal line

Person with recessive allele that does not show trait is a carrier; can pass trait to children

Autosome; any chromosome other than X or Y; a non-sex chromosome

Autosomal recessive disorder (figure 11.10, page 195); affected individual must be homozygous recessive to have trait; affected individual can have unaffected parents; gene located on one of the autosomes; males and females affected equally; heterozygotes are carriers;

Autosomal dominant disorder (figure 11.13, page 196); one copy of dominant allele results in having trait; gene located on one of the autosomes; males and females affected equally;

Beyond Mendelian Inheritance

                Multiple alleles; more than two alleles for a trait; blood type has three alleles (A,B,O); individual inherits two of them;

                Codominance; two different alleles present; both expressed;

                Incomplete dominance; heterozygote has intermediate phenotype (cross red flower with white flower; first generation is pink)

                Pleiotropy; single gene affects many traits; Marfan syndrome (figure 11.15, page 199)

                Epistatic interactions; one gene can override another;

                Polygenic; many genes affect one trait;

                Multifactorial traits; many genes plus environment affect phenotype;

                X-linked inheritance; gene is on X chromosome; males have only one X chromosome, so they have trait if they inherit recessive allele from mother;  females have two X chromosomes and can be homozygous or heterozygous; trait appears more in males than females;

1. Briefly describe each of the stages of aerobic cellular respiration. Name the inputs and outputs of each stage and where they take place.

 Preparatory reaction: takes place in the mitochondria. Pyruvate is broken down from a 3-carbon molecule to a 2-carbon acetyl group, and a 1-carbon molecule is released. Reaction occurs twice per glucose molecule.

The citric acid cycle: takes place in the mitochondria. Each acetyl CoA combines with oxaloacetate to form citrate, several steps are used to convert citrate back into oxaloacetate, and during these steps NAD+ is reduced to NADH

The electron transport chain: A series of carriers on the inner membrane of the mitochondria. NADH from the citric acid cycle passes its electrons to the first carrier, which passes them to the next carrier, etc. The final electron acceptor is oxygen. After oxygen receives its electrons it is combined with hydrogen ions and becomes water.

2. Define oxidation and reduction and describe a redox reaction.

3. Define anabolism, catabolism and metabolism

 Anabolism: Reactions that build up big molecules from smaller ones

Catabolism: Reactions that break down big molecules into smaller ones

Metabolism: All chemical reactions that take place in cells

4. What is the purpose of oxygen in aerobic cellular respiration?

 The purpose of oxygen in aerobic cellular respiration is to produce CO2 and H2O.

5. What is the main electron carrier for aerobic cellular respiration?

The main electron carrier for aerobic cellular respiration is NADH.

1. Briefly describe how G3P is produced in the Calvin cycle. Where does it take place?

G3P is produced when carbon dioxide enters the Calvinist cycle, the CO2 then turns into C6 which then turns into 3PG. 3PG then turns into BPG which in turn turns into G3P.

 The Calvin cycle is a series of reactions that produce carbohydrates before returning to the starting point. The CAlvin cycle does not require light, but uses products of light reaction to reduce carbon dioxide from the atmosphere

2. Briefly describe how the light-dependent reactions of photosynthesis produce NADPH.  Where do they take place?

 During the light reactions, solar energy energizes electrons, which move down an electron transport chain. As the electrons move down the chain, which consists of proteins in the cell membrane, energy is released and captured to produce ATP molecules. Energized electrons are also taken up by NADP+, which is reduced and becomes NADPH. 

The light reaction takes place on the thylakoids.

3. What types of plants use C4 photosynthesis and CAM photosynthesis? How do these processes differ from C3 (the most common) photosynthesis?

The type of plants that use CAM photosynthesis are a family of flowering succulent plants, like pineapples and cactus, that live in warm dry regions of the world.

The type of plants that use C4 photosynthesis are plants that live in hot dry climates like sugar cane, corn, and Bermuda grass.

C3 photosynthesis produces a 3-carbon molecule while C4 photosynthesis and CAM photosynthesis produce a 4-carbon molecule

1. Briefly describe the stages of the cell cycle.

G1: Normal growth and function

S: DNA replication

G2: Final preparation for division

M: Mitosis and cytokinesis(cell division)

2. Briefly describe the checkpoints of the cell cycle.

 G1:Is cell damaged: can it be repaired

G2: Was DNA replicated properly

M: Are chromosomes lined up properly in cell center

3. Briefly describe the phases of mitosis.

 Prophase: chromatin condense into chromosomes; nuclear envelope is formed

Metaphase: Chromosomes line up in the middle of the cell

Anaphase: Sister chromatids separate and move to opposite ends of the cell

Telophase: Chromosomes reach the ends of the cell; nuclear envelope reforms

Cytokinesis: Cell is divided into two cells.

4. Briefly describe the process of binary fission.

Binary fission: Splitting of a parent cell into two daughter cells; serves as an asexual form of reproduction in bacteria.

1. Define the following terms:  Karyotype, Gamete, Autosome, Homologous chromosome, Chromatid

Homologous chromosome: Member or pair of chromosomes that are alike and come together in synapses during prophase of the first meiotic division

Chromatid: Following replication, a chromosome consists of a pair of sister chromatids, held together at the centromere; each chromatid is comprised of a single DNA helix

Autosome: Chromosome pairs that are the same between the sexes; in humans, all but the X and Y chromosomes

Gamete: Haploid sex cell

Karyotype: A pictorial display of human chromosomes arranged by pairs according to their size, shape, and general appearance in meiotic metaphase.

2. Briefly describe the phases of meiosis.

Prophase I: Chromatin condenses into chromosomes; nuclear envelope fragments; homologues pair up; crossing over occurs between the non sister chromatids

Metaphase I: Homologues pairs lined up at metaphase plate in the center of the cell

Anaphase I: Homologues separate and are pulled to opposite poles

Telophase I: Chromosomes reach poles; new nuclear envelope may form

Cytokinesis: Divides into two cells

Prophase II: Cells have one chromosomes from each homologues pair

Metaphase II: Chromosomes align at the metaphase plate in the center of the cell

Anaphase II: Sister chromatids separate and are pulled to opposite ends of the cell

Telophase II: Chromosomes reach the ends of the cell; new nuclear envelope is formed

Cytokinesis: Divides cells into a total of four cells

3. Define diploid and haploid and relate each to the number of chromosomes in a human cell.

Diploid: Cell condition in which two of each type of chromosome are present; Humans have 46 chromosomes in diploid cells(two sets of chromosomes)

Haploid: Cell condition in which only one of each type of chromosome is present(one set of chromosomes)

4. Describe the processes that lead to genetic diversity in sexual reproduction.

 Crossing Over: Exchange of genetic material between nonsister chromatids in homologues; homologues pair up in early meiosis and parts of chromatids switch pieces; result in chromatids different than either parent chromosome

Independent assortment: Homologue pairs separate independently in metaphase I; maternal and paternal chromosomes may be oriented toward either pole.

Fertilization: Union of male and female gametes; offspring have some characteristics of each parent and are not identical to either parent or any of their siblings.

5. Describe aneuploidy.

More or fewer than the normal number of chromosomes; results from nondisjunction; most common in Down syndrome.

1. Define the following terms: Gene, Homozygous, Heterozygous, Dominant, Recessive

 Homozygous: Two identical alleles

Heterozygous: Two different alleles

Dominant: The allele expressed in the heterozygous individual (T)

Recessive: The allele masked in the heterozygous individual (t)

Gene: Unit of heredity existing in alleles on the chromosomes; in diploid organisms, typically two alleles are inherited, one from each parent.

2. Using seed color in pea plants, briefly define allele, genotype and phenotype and describe how they are related.

 Allele is the alternative form of a gene. In Menel’s pea plant experiment the genotype is the makeup of the pea or the fertilization that was received. The phenotype is the physical appearance of the pea.