Ch 10: Introduction to Genetics Review
Topics
Meiosis
a. What is the difference between diploid and haploid cells? DIPLOID CELLS HAVE TWO SETS OF CHROMOSOMES; HAPLOID CELLS HAVE ONE
b. What symbols are used for diploid and haploid? 2n (diploid) OR n (haploid)
c. What process of cell division creates diploid cells, and what process creates haploid cells? MITOSIS CREATES DIPLOID; MEIOSIS CREATES HAPLOID
d. What are homologous chromosomes? CORRESPONDING CHROMOSOMES
e. What structure do they form during Prophase I? TETRADS
f. What is crossing-over? When does it occur? Why is it important? WHEN ALLELES ARE EXCHANGED BETWEEN HOMOLOGOUS CHROMOSOMES AND RESULT IN NEW COMBINATIONS OF ALLELES IN SEX CELLS
g. Briefly describe what happens during each phase of meiosis.
i. INTERPHASE I: CHROMOSOMES REPLICATED, CELL GROWS, ORGANELLES REPLICATE
ii. PROPHASE I: HOMOLOGOUS CHROMOSOMES FORM TETRADS, CROSSING OVER OCCURS
iii. METAPHASE I: TETRADS LINE UP IN THE CENTER OF THE CELL ATTACHED TO SPINDLE FIBERS
iv. ANAPHASE I: TETRADS ARE PULLED APART BY THE SHORTENING OF THE SPINDLE FIBERS; CELLS BECOMING HAPLOID
v. TELOPHASE I & CYTOKINESIS: CHROMOSOMES MOVE TO OPPOSITE ENDS OF THE CELL, NUCLEAR MEMBRANE REFORMS, CYTOPLASM SPLITS AND CELL SPLITS INTO TWO HAPLOID CELLS
vi. PROPHASE II: NO REPLICATION OF CHROMOSOMES HAPPENS, STARTS WITH TWO HAPLOID DAUGHTER CELLS
vii. METAPHASE II: CHROMOSOMES LINE UP IN THE CENTER OF THE CELL ATTACHED TO SPINDLE FIBERS
viii. ANAPHASE II: SISTER CHROMATIDS ARE PULLED APART BY SHORTENING OF SPINDLE FIBERS
ix. TELOPHASE II & CYTOKINESIS: CHROMOSOMES MOVE TO OPPOSITE ENDS OF CELL, NUCLEAR MEMBRANE REFORMS, CYTOPLASM SPLITS THE CELLS INTO FOUR SEX CELLS (SPERM OR EGGS)
h. How many times is the DNA replicated in meiosis? When does it happen? ONCE; INTERPHASE I
i. How many cells are created during meiosis, and how do they compare to the parent cell? 4 CELLS – THEY ARE HAPLOID (PARENT IS DIPLOID), SEX CELLS – EITHER 4 SPERM OR 1 EGG & 3 POLAR BODIES
j. What type of cells is created during Meiosis? GAMETES OR SEX CELLS AND THEY ARE HAPLOID (ONLY HAVE 1 SET OF CHROMOSOMES)
Mendel and Punnett Squares
1. Briefly describe Mendel’s experiments. USED PEA PLANTS TO LOOK AT INHERITANCE PATTERNS OF 7 DIFFERENT TRAITS
2. Label each generation (P, F1, and F2) as true-breeding or hybrid. P – TRUE-BREEDING; F1 – TRUE-BREEDING; F2 - HYBRID
3. Give the results of each experiment (genotype and phenotype of F1, and F2 generations). F1 – ALL HETEROZYGOUS GENOTYPES, ALL DISPLAY DOMINANT TRAITS; F2 – 3 DOMINANT AND 1 RECESSIVE GENOTYPE, 3 DISPLAY DOMINANT TRAITS, 1 DISPLAYS RECESSIVE
4. Determine whether the experiment was done with self- or cross-pollination. F1 DONE WITH CROSS POLLINATION; F2 DONE WITH SELF-POLLINATION
5. What does the principle of dominance state? ONE ALLELE IS DOMINANT OVER THE OTHER; DOMINANT TRAIT IS ALWAYS DISPLAYED WHEN PRESENT; RECESSIVE IS ONLY DISPLAYED WHEN IT’S THE ONLY ONE PRESENT
6. What is the principle of segregation? THE TWO COPIES OF A GENE AN INDIVIDUAL HAS SEPARATE DURING GAMETE FORMATION; COPY IS CHOSEN AT RANDOM
7. What is the difference between genotype and phenotype? GENOTYPE IS THE LETTERS USED (Bb, bb, BB) AND PHENOTYPE IS THE ACTUAL PHYSICAL TRAIT (BROWN HAIR, BROWN EYES, DETACHED EARLOBES, ETC.)
8. Given a trait with two alleles (T and t), what are the homozygous recessive, heterozygous, and homozygous dominant genotypes? HR – tt, HE – Tt, HD – TT
9. What phenotypes does each of those genotypes display? tt – recessive; HE – dominant; HD – dominant
10. What is probability? RULES THAT PREDICT THE LIKELIHOOD OF AN EVENT OCCURRING
11. What can Punnett squares be used for, but what can’t they tell you? CAN GIVE ALL POSSIBLE OUTCOMES FOR THE CROSS BETWEEN TWO PARENTS; CAN’T PREDICT THE ACTUAL OUTCOMES OF THE CROSS
12. What is the principle of independent assortment? EACH GENE SEGREGATES ON ITS OWN; THE INHERITANCE OF ONE TRAIT DOESN’T INFLUENCE THE INHERITANCE OF ANOTHER
13. Review monohybrid Punnett Squares and make sure that you can find the correct results and ratios.
Beyond Mendelian Genetics
1. What is polyploidy? Give an example. POLYPLOIDY IS WHEN AN ORGANISM HAS ONE OR MORE EXTRA SETS OF ALL CHROMOSOMES (3N, 6N, etc.). An example is wheat, oats, OR strawberries. It makes healthier crops.
2. What are linked genes? GENES THAT ARE LOCATED ON THE SAME CHROMOSOMES
3. Can linked genes separate from each other, and what makes it more possible? YES BECAUSE OF CROSSING OVER; THE FARTHER APART THEY ARE, THE MORE LIKELY THEY ARE TO CROSS OVER AND SEPARATE DURING MEIOSIS