Keystone Review 2

1. Keystone Review 2 Cell cycle through ecology

2. Cell cycle • There are two different types of cell reproduction, based on WHICH type of cells are being reproduced • -Body cells, or somatic cells, undergo MITOSIS • -Sex cells, or gametes, undergo MEIOSIS • -Prokaryotic cells, like bacteria, undergo a different process called binary fission • -binary fission is the splitting of the entire cell into two new cells.

3. Cell cycle • Chromosome structure. How many chromosomes do humans in each cell? Chromatid Centromere

4. Cell cycle • Both mitosis and meiosis consist of several phases: • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

5. Cell cycle • Interphase • Interphase has three stages • G1: first growth phase. In G1 the cell grows bigger so that it does not get smaller and smaller with each reproduction • S: synthesis phase. In S phase, the cell replicates it’s DNA (DNA replication!). The cell does this so that each time it reproduces, it does not lose half of it’s DNA to the new cell. If the cell DID lose half it’s DNA to the new cell, eventually there would be no DNA left in new cells that are being produced. • G2: second growth phase. In G2 the cell grows more and prepares for EITHER mitosis or meiosis (depending on the type of cell, right?!)

6. Cell cycle • Mitosis • Interphase (previously covered) • prophase: in this phase the cell’s nuclear membrane starts to dissolve and the chromosomes are free-floating in the cell. The chromosomes begin to uncoil so that they are easier to move around. Spindle fibers begin to form. They are responsible for moving chromosomes around. • Metaphase: in this phase, the chromosomes line up on the equator of the cell.

7. Cell cycle • Anaphase: in this phase, the chromosomes are being pulled to opposite poles of the cell by the spindle fibers. Spindle fibers attach to the chromosome at the centromere. The chromosomes are split into smaller segments, but are still referred to as chromosomes! • Telophase: in the phase, the cell’s cytoplasm beings to separate into two cells

8. Prophase Metaphase Anaphase Telophase Cytokinesis

9. Cell cycle • Mitosis • -Cytokinesis: occurs after telophase, but it technically not a “phase” of mitosis or meiosis. During cytokinesis, the cytoplasm of the cell divides, producing two cells

10. Cell cycle • Meiosis • -Meiosis goes through the cell cycle twice. Why? Because gametes need only half of the amount of chromosomes as somatic cells do. This is because two gametes must join together (sperm + egg) to produce a zygote, or fertilized egg. • If gametes had a full set of chromosomes, sperm + egg= double the amount of chromosomes needed. More than the required amount of chromosomes results in genetic disorders/ even death of the cell.

11. Cell cycle • Meiosis 1 • Interphase (previously covered) • Prophase 1: nuclear membrane dissolves, chromosomes uncoil. • Metaphase 1: chromosomes line up on the cell’s equator with their homologous pair

12. Cell cycle • Meiosis • 4. Anaphase 1: Homologous chromosomes separate to either pole of the cell. They are pulled by spindle fibers attached to their centromeres. • 5. Telophase 1: The cell prepares for cytokinesis

13. Cell cycle • Meiosis • The cell does NOT go through interphase twice. Why? Because during interphase, the cell replicates it’s DNA (during S phase), and this would result in again, a doubled amount of chromosomes for a gamete cell.

14. Cell cycle • Meiosis 2 • Prophase 2: cell’s nuclear membrane dissolves, chromosomes uncoil • Metaphase 2: chromosomes line up on the equator of the cell, pulled there by spindle fibers • Anaphase 2: spindle fibers, attached to the chromosome’s centromere, pull the chromosomes to opposite poles of the cell. The chromosomes are now smaller segments, but still referred to as chromosomes! • Telophase 2: the cell prepares for cytokinesis

15. Prophase 1 Metaphase 1-homologs line up Anaphase 1 Telophase 1 Cytokinesis

16. Prophase 2 Metaphase 2 Anaphase 2 Telophase 2 Cytokinesis

17. Genetics • Allele: a form of a gene such as B or b. Every person has (at least) two for each gene • Gene: a segment of a chromosome that codes for a specific trait, such as hair color • Genotype: the alleles you have for a certain trait • ex: BB, Bb, bb • Phenotype: the physical trait that you have (because of the alleles you have • ex: brown hair, blonde hair

18. Genetics • Mendel: a monk who first studied genetics using pea plants from his garden. He discovered dominant/recessive traits.

19. F1 SPERM P p P PP Pp p Pp pp F1 E G G S P and p are the two alleles for the character of flower color. PP is one combination which = purple flowers Pp is combination which = purple flowers pp is one combination which = white flowers There are only TWO traits, purple or white

20. Genetics • Dominant: the form of the character that is expressed physically. It is represented by a capital letter, such as B • Recessive: the form of the character that is not expressed physically, unless there are two recessive alleles. It is represented by a lower case letter, such as b • Heterozygous: two alleles that are different, one dominant and one recessive, Bb • Homozygous: two alleles that are the same • -homozygous dominant: two dominant, BB • -homozygous recessive: two recessive, bb

22. Genetics • Punnett square: a tool used to determine the possible genotypes and phenotypes of offspring between two parents • Monohybrid cross: examines ONE trait at a time

23. Genetics • Dihybrid cross: examines two traits at a time. • *special technique for setting up the punnett square • FOIL • Parent= GgYy • Possible gametes: GY, Gy, gY, gy

24. Genetics • Complex patterns of heredity: traits that don’t follow Mendel’s rules of dominant/recessive. • -sex-linked: traits that are carried on the X or Y chromosomes • -multiple alleles: traits that are controlled by more than two alleles • -incomplete dominance: traits that don’t show just dominant/recessive phenotypes • -codominance: traits that don’t have a recessive alleles or phenotype

25. Genetics • Incomplete dominance: the dominant gene is not “dominant” enough to completely mask the recessive gene in a heterozygous genotype. • Ex: flower color in snapdragon flowers

26. genetics • Codominance: there is no recessive gene. There are two genes that are equally dominant. We cannot use our normal capital/lower case lettering system. • Instead we use superscripts: IGIG and IBIB

27. genetics • Multiple alleles: there are more than two alleles that control a trait. There are still dominant and recessive genes, but since there might be more than one, we use superscripts.

28. genetics

29. genetics • Sex-linked: the genes for these traits are found on the X or Y chromosomes • XX=female • XY=male

30. genetics • Polygenetic inheritance: when more than one gene controls a trait (not just more than one allele, that’s called multiple alleles). Results in many variations, not just two (one dominant, one recessive). • ex: Skin color, hair color, eye color • Epigenetics: traits that are influenced by the environment • ex: • Hydrangea: same genotype for flower color express different phenotypes depending on the acidity of the soil • Articfox: fur color is affected by temperature. During the summer, the fox produces enzymes that makes pigments. These pigments darken the fox’s coat to a reddish brown so the fox can blend in with the summer landscape • Humanheight: influenced by nutrition. • Humanskin: influenced by exposure to sun

31. genetics • Pedigree: a tool used to determine how traits are passed down through generations

32. evolution • How did life form on Earth? • The Bubble Model • 1. gases (from underneath the Earth’s crust) were trapped in underwater bubbles • 2. gases underwent chemical reactions • 3. gases were ejected into the atmosphere • 4. gases underwent further reactions • 5. simple and complex compounds fell into the oceans, such as carbon, oxygen, and nitrogen • 6. These molecules formed RNA, which made the first proteins • 7. Proteins are the building blocks of all living things

33. evolution • Endosymbiosis: how eukaryotes were formed from prokaryotes

34. evolution • The move to dry land • -Life on Earth was unsafe due to the extreme heat and ultraviolet radiation from the sun • -Ozone was formed and served as a protective barrier from ultraviolet radiation • -ozone formed when oxygen, released by prokaryotes performing photosynthesis underwater, reacted with sunlight (O3).

35. Evolution • Other ways the Earth has changed: • -Continental drift: the continents sit on plates that can shift/move. The continents were once all connected and created a large land mass known as Pangaea. • -Species have evolved

36. evolution • How have species evolved? • Darwin was the first to study and develop theories about how evolution was occurring in plant and animals. He studied finches on the Galapagos Islands.

37. evolution • Species: a group of similar organisms that can interbreed successfully, and produce successful offspring • ex: humans. • nonex: donkeys (horse + mule). They are sterile • Population: a species living in a particular area • ex: humans in pennsylvania

38. evolution • Natural selection: the environment “chooses” which individuals survive based on which traits they possess • ex: brown deer are naturally selected FOR because they are able to blend in with their environment and avoid predators. White deer are naturally selected AGAINST because they stick out in their environment. • Do traits disappear?

39. evolution • Adaptation: when a particular trait is selected for over time, because it is advantageous, and therefore becomes more common in the population • Ex: peppered moths (lab from class)

40. evolution • Fitness: the measure of how successful a particular organism is. We say its measured in “grandchildren”. The more offspring you produce, the more fit you are because you are surviving long enough to reproduce • ex: a cod laying 1 million eggs (all survive, for example), is more fit than a panda who only has one cub.

41. evolution • Types of natural selection • Disruptive: natural selection shifts so that two traits are favored • Stabilizing: natural selection shifts slightly so that the average trait is again favored • Directional: natural selection shifts in one direction, in favor of one trait

42. evolution • Speciation: the formation of a species. Two types of speciation are convergence and divergence. • -Divergence: the accumulation of differences among organisms that share a common ancestor • -Convergence: the accumulation of differences among organisms that come from different lineages

43. evolution • How does speciation occur? 3 ways • Reproductive isolation: a species begins to diverge because of mate preferences. They choose to stop breeding as a whole and evolution occurs in the two different groups. • Ex: flies and starch/sugar food preference • Geographical isolation: a species begins to diverge because they are physically separated and can no longer breed. The two groups evolve separately. • Ex: pup fish in death valley • Behavioral isolation: a species begins to diverge because they have different behaviors and they choose to stop breeding as a whole. Evolution occurs separately in the two groups. • Ex: blue footed boobiebird mating dances

44. evolution • RESULTS of the 3 types of speciation • Sympatric speciation: when two new species diverge because of reproductive or behavioral differences. They are from the same homeland, but chose not to breed. • Allopatric speciation: when two new species diverge because of geographic differences. They are from different homelands and can therefore not breed

45. evolution • Types of evidence: • Molecular/DNA evidence: similar DNA means there is a shared ancestor • Comparative anatomy: similar bone structures/physical attributes means there is a shared ancestor • Embryology: similar embryo and fetus structure/appearance means there is a shared ancestor • Fossils: similar ancient organisms means that organisms that evolved over time, or that we came from those organisms.

46. Evolution

47. Taxonomy • Taxonomy is the classification of living things. • Classification system: domain, kingdom, phylum, class, order, family, genus species. Genus and species make up an organism’s scientific name • ex: Pantherapardus

48. taxonomy

49. taxonomy • We can determine when certain traits evolved over time, as well as which organisms are more closely related by studying cladistics and phylogeny.

50. Taxonomy