Terminology
- Microtubule Organizing Center (MTOC)
- Birthplace of microtubule spindles, from the centrosomes.
- Metaphase Plate
- The center line where the chromosomes line up during metaphase.
- Kinetochore
- A protein wrapped around the centromere and binds to the microtubule spindles.
- Microtubules made of tubulin protein attach to centromere at kinetocore.
- Protein complex around the centromere.
- "Beads on a string"
- Beads are the nucleosomes.
- DNA is wrapped around histones.
Cell Cycle
Condensed chromosomes only exist in metaphase, otherwise they are loosely condensed in order to be read.
- G0
- ?
- S
- Chromatids are held together at centromere (CEN).
- Telophase
- Nuclear membranes reform around split chromosomes.
- Cytokinesis
- Plants form vesicles where metaphase plate is that forms a new cell wall.
- Animals cleave the cell in two along the metaphase plate using actin.
Centromere Locations
- Acrocentric
- ?
- Metacentric
- ?
- Submetacentric
- ?
- Telocentric
- ?
Chromosome Visualizations
- How to distinguish chromosomes?
- Use their size, bonding patterns.
- Staining
- Displays bonding patterns
- Karyotype
- Microscopy
- Idiogram
- Drawn
Aneuploidy
- Monosomy
- ?
- Trisomy
- ?
- Nullsomy
- ?
- Tetrasomy
- ?
Study Guide
Resources: Chapters 1-2 the textbook glossary, index, syllabus, canvas, and lab!
Mitosis
- When does mitosis begin in an organism; when does it end?
- How do we know that chromosomes does not correlate with complexity? Go here: and tell me how many chromosomes are in the genome of your favorite animal, along with its common name and its genus + species. Note: those are diploid chromosome counts. What is your favorite organism with a lot of chromosome, and is your favorite organism with very few chromosomes - this will be a discussion on canvas - for points/credit. :)
- https://en.wikipedia.org/wiki/List_of_organisms_by_chromosome_count
- A chromosome in G2 of cell cycle looks like two chromosomes, but it is not. It is a single chromosome in the replicated state! How can you tell the difference? What structures do you count, to count chromosomes?
- What is the difference between a Locus and an Allele? For a gene, there may be many alleles in the population - what's defines the 'wildtype', and what defines 'mutant'?
- What is the difference between a karyotype and an idiogram (this reviews from lecture 1 slide 27)? How do we identify the chromosomes under the microscopes?
- Why do metaphase chromosomes (which are the ones we look at in a karyotype) look like an "X"?
- What does 'heterozygote' mean?
- List 5 subphases of M-phase mitosis: what comes before M-phase, what comes after it?
- Know what happens to the DNA in all 5 stages of Mitosis.
- Where is the kinetochore and why is it so important? What is its purpose?
- What is a microtubule, how is it related to the mitotic spindle, how does it lengthen/shorten, when in Mitosis does it lengthen/shorten. What happens when there are errors in these functions?
- What is the MTOC, what is the other name for it?
- What is cytokinesis, and how is it different in animals v. plants?
- 46, XX means what? 46, XY means what?
- Define aneuploidy.
- What is it called when a chromosome does not split properly in mitosis anaphase?
- If the mitotic spindle is not formed correctly, what can result? Name one human disorder is caused by this - name the disorder, what chromosome is affected, and how is that karyotype/genotype written?
- What does diploid mean? How many copies of each gene does a diploid carry?
- What is a metaphase plate?
- You are examining human chromosomes 2, 7, 22, X and Y ... which is largest, which is smallest? Which are autosomes, which are sex chromosomes?
- Diploid cells in a bug have 10 chromosomes in each nucleus. Tell me what is the 2n number, what is the 1n number, and how many chromosomes vs. sister-chromatids are found in that cell at each stage: G1, S, G2, Prophase, Prometaphase, Metaphase, Anaphase, Telophase.
- Know where the chromosome sits on these 4 types of chromosomes: Metacentric, Submetacentric, Acrocentric, Telocentric.
- For a heterozygote gene B (Bb genotype) draw the homologous pair of chromosomes in G1 before S, then in G2 after S, at the mitotic metaphase plate. Do they pair up in mitosis ...?