1. 2nd quarter eqt
Study Guide Answers

2. Cell cycle: Interphase, Mitosis, Cytokinesis
Interphase: G1 (growth; longest part), S (DNA replication), G2 (make structures
necessary for mitosis)
During interphase the chromosomes are in the form of chromatin
Mitosis
Prophase- spindle forms, sister chromatids attach at the centromere, nucleus
and nucleolus disappear, chromosomes are visible, spindle fibers
attach to centromeres
Metaphase- spindle moves chromosomes to equator of cell
Anaphase- sister chromatids separate at centromere; spindle pulls
chromosomes to opposite poles
Telophase- nucleus reforms around the chromosomes at each pole; spindle
disappears, nucleolus reappears, chromosomes return to
chromatin; happens at the same time as cytokinesis
Cytokinesis- in animal cells a cleavage furrow forms to separate the two new
cells; in plant cells a cell plate (becomes cell wall) forms to
separate the two new cells

4. 2. Meiosis Meiosis I (one cell) Meiosis II (two cells)
Prophase 1- Homologous chromosomes pair up; crossing over occurs
Metaphase 1- Homologous chromosomes line up on the equator
Anaphase 1- Homologous chromosomes separate and move to opposite poles; sister chromatids remain
attached at the centromeres
Telophase 1 – the cell divides into two; nucleus reforms around the chromosomes
THERE IS EITHER NO INTERPHASE OR IF IT OCCURS IT IS VERY SHORT! DNA DOES NOT
DUPLICATE!!
Meiosis II (two cells)
Prophase 2 -Nucleus disappears; spindle attaches to the chromatids
Metaphase 2- chromatids line up on the equator
Anaphase 2- Sister chromatids separate at the centromere and move to opposite poles
Telophase 2- the two cells divide in half; four genetically different haploid cells are produced

6. 3. Diploid v. Haploid
Diploid- 2 complete sets of chromosomes; all cells except gametes; 2n
Haploid- 1 set of chromosomes; gametes only; n

7. 4. Beginning and ending products of mitosis and meiosis
Mitosis- 1 diploid cell produces 2 genetically identical diploid cells
Meiosis- 1 diploid cell produces 4 genetically different haploid cells

8. #5 Synapsis – two homologous chromosomes pairing up next to each other Tetrad – the group of 4 chromosomes formed during synapsis Crossing over – the non-sister chromatids of the tetrad cross legs, break off and exchange parts; creates genetic diversity Sister chromatids – an original chromosome and its copy; attached to each other by the centromere Centromere – site where sister chromatids are attached Homologous chromosomes – chromosomes that are the same size and shape; contain similar information; you get one from each parent

9. #6 Karyotypes

10. #7 Purpose of Mitosis and Meiosis
Mitosis- create two identical nuclei
Meiosis- create haploid gametes

11. #8 Chromosome differences in prokaryotes and eukaryotes
Prokaryotes- 1 circular chromosome
Eukaryotes- any number of linear-shaped chromosomes

12. #9 Cell Plate
Forms in between the new cells formed during mitosis of plant cells; becomes the cell wall.

13. #10 Spindle
The spindle is created during prophase of mitosis and meiosis. It attaches to chromosomes and eventually cause separation of sister chromatids and/or homologous chromosomes.

14. #13- Down’s Syndrome Caused by an extra copy of chromosome 21
Called trisomy-21

15. #16- Genes
Sections of DNA that code for a protein

16. #17- Mendel’s Laws
Law of Dominance- hybrid offspring show the dominant form of the trait
Law of Segregation- when gametes are formed, the alleles for a trait separate; each gamete can carry only one allele from the pair
Law of Independent Assortment- alleles for different traits are inherited independently of each other; the inheritance of one trait does not affect the inheritance of another

17. #18- DNA Replication
DNA uncoils and then unzipped; unpaired bases in the nucleus pair with their complementary bases on the open strand; two new identical strands of DNA are formed
Semi-conservative replication

18. #19 Complementary Bases
A and T
C and G
In RNA, U replaces T

19. #21 Genotypic and Phenotypic Ratios
Genotypic ratios- show the ratios of the different genotypes
Example: BB:Bb:bb is 1:2:1
Phenotypic ratios- show the ratio of the phenotypes
Example: Dominant to recessive 3:1

20. #22 Genotype and Phenotype
Genotype- letter combination (BB, Bb, bb)
Phenotype- looks (brown, blue)

21. #23 Main function of DNA
Store genetic material (instructions for making proteins)

22. #24 Sex Cells v. Somatic Cells
Somatic cells- body cells; all cells except gametes; always diploid
Sex Cells- gametes; egg and sperm; always haploid

23. #25 DNA v. RNA RNA DNA Double stranded Deoxyribose sugar A, C, T, G
Single stranded
Ribose sugar
A, C, G, U
3 kinds: mRNA, tRNA, rRNA
mRNA
tRNA

24. #26 Colorblindness
More common in males than females because it is a sex- linked recessive disorder
Recessive allele is on the X chromosome; because males have only one X chromosome, they do not have the ability to hide the recessive allele if they inherit it

25. #27 DNA Replication
Happens every time a cell divides

26. #29 Nitrogenous bases
DNA – A, C, T, G
RNA- A, C, G, U

27. #31 Chargaff’s rule
The amount of A= the amount of T in a sample of DNA; the amount of C = the amount of G in a sample of DNA

28. #32 Genotypes
Male- XY
Female- XX

29. #33 Homozygous and Heterozygous
Homozygous- genotypes with identical alleles
Can be bigbig or little little
BB or bb
Purebreds, true breeding
Heterozygous- genotypes with different alleles
Biglittle Bb
Hybrids, carriers

30. #34 Protein Synthesis Transcription mRNA copies DNA in the nucleus
mRNA leaves the nucleus and goes to the ribosome
Translation
Codons (3 letter codes on mRNA) are read by the anticodons on tRNA
tRNA finds the amino acid that the codons code for and carries them to the ribosome
mRNA enters the ribosome where the ribsome attaches the amino acids together to form a protein
Protein starts when the ribosomes gets the “start” code
Protein is finished and released when the ribosome receives the “stop” code

31. Translation

32. #35 Photosynthesis v. Respiration
Uses energy to produce sugars
Chloroplasts
Autotrophs only
Uses sugar to produce energy (ATP)
Mitochondrion
Autotrophs and Heterotrophs

34. #36 Reactants and Products
Photosynthesis
Reactants- carbon dioxide and water
Products- sugar (glucose) and oxygen
Respiration
Reactants – glucose and oxygen
Products- water, carbon dioxide and ATP (energy)

35. #40 Equations
Photosynthesis
Respiration

36. #42 Heterotrophs and Autotrophs
Heterotrophs cannot produce their own food
Autotrophs can produce their own food

37. #43 Pigments
Pigments are chemicals that absorb certain wavelengths of light and reflect others
Chlorophyll is a pigment that absorbs all colors and reflects green

38. #44 Chloroplast and Mitochondrion

39. #45
Chlorophyll is located in the thylakoids of the chloroplasts

40. #46
Both respiration and photosynthesis produce the raw materials (reactants) for the other process

41. #47
Anaerobic –requires no oxygen
Aerobic- requires oxygen

42. #48
Alcoholic fermentation produces alcohol and carbon dioxide; happens in yeast
Lactic acid fermentation produces lactic acid and carbon dioxide; happens in muscle cells

43. #50
Co-dominance- both alleles are equally dominant and are expressed equally in the hybrids
Example- chickens can have black feathers (BB), white feathers (WW) or black and white (BW)

44. #51 Incomplete Dominance
One allele is not completely dominant; hybrids are a blend of the two phenoytpes
Example; Black fur (BB), White fur (WW), Gray fur (BW)

45. #54
Both heterozygous

46. #55
9:3:3:1

47. #56 F1- all were hybrids and had the dominant phenotype
F2- genotypic ratio of 1:2:1; phenotypic ratio of 3:1 (dominant : recessive)

48. #57 Different forms of the trait
B- dominant allele; b- recessive allele

49. #58
Chromatin is the stringy form that chromosomes exist in most of the time