2nd quarter eqt Study Guide Answers

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

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

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

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

#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

#6 Karyotypes

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

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

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

#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.

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

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

#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

#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

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

#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

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

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

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

#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

#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

#27 DNA Replication Happens every time a cell divides

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

#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

#32 Genotypes Male- XY Female- XX

#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

#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

Translation

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

#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)

#40 Equations Photosynthesis Respiration

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

#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

#44 Chloroplast and Mitochondrion

#45 Chlorophyll is located in the thylakoids of the chloroplasts

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

#47 Anaerobic –requires no oxygen Aerobic- requires oxygen

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

#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)

#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)

#54 Both heterozygous

#55 9:3:3:1

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

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

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