Chapter 10 Flashcards
The Cell Cycle
A cell’s DNA
Genome
Discrete pieces or strands of DNA
chromosome
How many complete sets or copies of the genome an organism carries in it’s cells
ploidy
Contains genes in exactly the same location
homologues
Gene location
locus
Proteins that assist in compacting the DNA into a size that will fit in the nucleus
histone
The resulting histone-DNA structures that resemble beads
nucleosome
DNA when it has formed nucleosomes
chromatin
Help to coil into a 30nm chromatin fiber
linker DNA
A region where each original strand and its newly made copy remain firmly connected to each other
centromere
Conjoined pair of chromosome and its copy
sister chromatid
Near the nuclei of animal cells; an organelle
centrosome
Two of these make of the centrosome and lie at right angles to each other
centriole
Nuclear division (mitosis)
karyokinesis
Separation of the cytoplasmic contents
cytokinesis
A protein structure that appear at the centromeres of each sister chromatid
kinetochores
Microtubule spindle fibers originating from the centrosomes that fully enlongate
mitotic spindle
The actin filaments pull the equator inwards to form this that will eventually split the membrane in two
cleavage furrow
Where the vesicles fuse from the center outward to form this in plants
cell plate
Programmed cellular death
apoptosis
A new membrane and cell wall constructed between two loops of DNA
septum
What are the two major phases of the cell cycle and what happens in each?
Interphase-the cell grows and DNA replicates; Mitosis-the replicated DNA and cytoplasmic contents separate and the cell divides
How is the genome of prokaryotes structurally different from the genome of most eukaryotes?
Prokaryotes have a single, circular molecule of double stranded DNA; eukaryotes have linear spiral double stranded DNA
In humans, how is the genome arranged? How many chromosomes in one set? How many sets do humans (and most animals and plants) contain? Where do the two sets come from?
Humans have 23 chromosomes that are diploid. Half from mom and half from dad
What is the difference between diploid and haploid cells?
Diploid have two copies while haploid have one
Which cells in the human body are diploid and which are haploid?
Somatic are diploid and gametes are haploid
How is DNA compacted to fit inside the nucleus of each cell? What are the three compaction levels of DNA?
DNA is would around histones which then form the nucleosome
Associate the events of a cell life cycle with the compaction levels of the DNA.
Interphase-Level 1 Compaction
What level of DNA compaction is chromatin? Chromosomes?
Chromatin are level 1 and chromosomes are level 3
What are the three stages of interphase? What happens in each?
G1 Phase-the cell accumulates the types and numbers of molecules needed for the next step
S Phase-DNA replication process occurs
G2 Phase-cell replenishes its energy and makes additional proteins needed for next steps
What types of environmental changes might affect G1?
Limited nutrient supply, irregular temperature, limited space
What happens to cells that cannot pass through G1?
They enter the G0 phase which is a phase of inactivity
During S phase of interphase, how are the copied strands of DNA organized? How are they held together?
They are held together by the centromere and are organized by sister chromatids
What is the centrosome? What does it do? Why is this important?
Two centrioles that lie at right angles from one another; They are used to pull the chromosomes apart during mitosis
What are the four phases of mitosis? What events happen at each phase?
Prophase, Metaphase, Anaphase, Telophase
Cytokinesis typically overlaps with which phase(s) of karyokinesis?
telophase
Describe events that result in the cleavage of animal cells into two daughter cells during cytokinesis. How does this process differ in plant cells?
A contractile ring composed of actin filaments forms around the cell just inside the plasma membrane at the site of the metaphase plate. The actin filaments pull the equator inward, forming a cleavage furrow that eventually cleaves the membrane in two
Plants form a cell plate
Name several events external to the cell that might regulate cell division.
Death of nearby cells(inhibit); Presence of Growth Promoting Hormone (initiate); Crowding of Cells (inhibition); Growing size of the cell (initiate
How many internal checkpoints occur during the cell cycle? Between which phases and events do each of them occur?
3; near end of G1, G2/M transition, during M
What types of things are the internal checkpoints examining?
Adequate reserves, sufficient cell size, Genomic DNA damaged, all chromosomes replicated, kinetochores of each pair of sister chromatids firmly anchored to at least two spindle fibers, each sister chromatid in the pair bonded to spindle fibers from opposite poles of the cell
What two specific groups of proteins are considered to be positive regulator molecules of the cell cycle?
Cyclins and CDK (cyclin dependent kinases)
How do the cyclins and CDKs interact to regulate the cell cycle?
Cyclins are the main regulatory molecules that determine the forward progress of the cell cycle
Cyclins regulate the cell cycle only when bound to CDKs
Name two specific proteins are considered to be negative regulator molecules.
P53 and p21
How do negative regulator molecules influence positive regulator molecules?
Halt the cell cycle when problematic conditions arise
Understand and describe the role of the p53 protein in regulating cell cycle progression.
Halts the cell cycle and recruits enzymes to repair the DNA; can trigger apoptosis to prevent duplication of damaged chromosome
Understand how mutations lead to cancerous growth (or not).
If mutations occur in the coding region, this can lead to cancer; if it is in a non-coding region, there is no functional change
What are proto-oncogenes? What are oncogenes?
proto-oncogenes are normal genes that code for positive cell cycle regulator while oncogenes are mutated genes that lead to an unnatural increase in the rate of cell cycle progression
What are tumor suppressor genes? Give an example of a tumor suppressor gene.
genes that code for negative cell cycle regulators; p53- if mutated, cancer is likely to form (more than 1/2 of cancer has mutation of p53)
How do prokaryotic cells divide? Name some differences between prokaryotic and eukaryotic cell division.
binary fission, can replicate both directions and creates a septum, there is also no histones or nucleosomes
