Lesson #14 Mitosis

Created by

Rudra Dutta

Cards (43)

What is the primary goal of cell reproduction?
To pass the cell’s genetic information onto daughter cells
What is the second goal of cell reproduction?
To pass sufficient amount of cellular contents to ensure daughter cell survival
How do prokaryotic cells reproduce?
By binary fission
Which organelles also divide by binary fission?
Mitochondria and chloroplasts
How do eukaryotic cells reproduce?
By mitosis and cytokinesis
What is mitosis?
Nuclear division
What is cytokinesis?
Cytoplasmic division
What is the similarity in cytokinesis for all eukaryotes?
It involves a temporary cytoskeletal machine
How do animal cells perform cytokinesis?
Using a contractile ring
How do plant cells perform cytokinesis?
By forming a cell plate
What is a karyotype?
The array of chromosomes in a species or individual
How does chromosome number relate to organism complexity?
Chromosome number is not correlated with organism complexity
What typically happens with the gain or loss of chromosomes?
It is usually fatal
What does haploid (1n) mean?
The complete set of chromosomes necessary to define the species
What does diploid (2n) mean?
Two complete sets of chromosomes
How do diploid cells typically originate?
Through sexual reproduction
What are homologous chromosomes?
Two copies of a chromosome pair
What are eukaryotic chromosomes composed of?
Chromatin, a complex of DNA and protein
How long is the typical human chromosome?
140 million nucleotides
How much DNA does a human cell contain?
6 feet of DNA
What are the two types of chromatin present in the nucleus?
Heterochromatin and euchromatin
What is heterochromatin?
Tightly-packed chromatin that is not expressed
What is euchromatin?
More loosely-packed chromatin that can be expressed
What are the stages of the eukaryotic cell cycle?
G1 phase: Primary growth phase
S phase: Replication/Synthesis phase
G2 phase: More growth & prep for M phase
M phase: Nuclear division + cytoplasmic division
What happens after the M phase?
The parent cell is split into two daughter cells which go through the cycle again
What phases make up interphase?
G1, S, and G2 phases
What are the stages of M phase?
G2: Prep for M phase, centrosome duplicates
Prophase: Bipolar spindle assembles, chromosomes condense
Prometaphase: Chromosomes attach to microtubules, orient, and congress
Metaphase: Chromosomes align at spindle equator
Anaphase: Sister chromatids separate, chromosomes move to poles
Telophase: Chromosomes decondense, nucleus begins to re-form
Cytokinesis: Animal - cleavage furrow, Plants - cell plate
What are the two irreversible points in the cell cycle?
Replication of genetic material and separation of sister chromatids
What happens at cell cycle checkpoints?
The process can be halted if errors are detected
What is the G1/S checkpoint?
Occurs late in G1, where the cell decides whether to commit to S phase
What factors are considered at the G1/S checkpoint?
Nutrients, cell size, and growth factors
What is the G2/M checkpoint?
The cell decides whether to commit to M phase
What does the spindle checkpoint evaluate?
Whether all chromosomes are aligned at the metaphase plate
How does cell cycle control differ in multicellular eukaryotes compared to single-cell eukaryotes?
Cells don’t reproduce until “told” to do so
What is the role of growth factor signals in multicellular organisms?
They are recognized by receptor proteins to move past the G1/S checkpoint
What happens if cell number and organization are not maintained in multicellular organisms?
It creates major problems for the organisms
What is cancer in relation to the cell cycle?
Involves uncontrolled cell proliferation and metastasis
What are proto-oncogenes?
Normal genes that can become oncogenes when mutated
What happens when proto-oncogenes are mutated?
They may be overexpressed or stuck in an "on" state
What is a gain-of-function mutation in proto-oncogenes?
Only one copy needs to be mutated