Ch 9 Flashcards
Name the three main stages on interphase.
G1
S
G2
The G in G1 stands for growth. What is happening to cell size during this phase? What is happening to the number of organelles in this phase?
- The cell is actively preparing for mitosis
2. It will need twice as many organelles
The S in the S phase is for synthesis. What exactly is happening to the DNA in the nucleus during this stage?
DNA is replication produces another complete set of chromosomes.
What new thing is being made in the cell during G2? What is the cell preparing for?
The cell synthesizes proteins that are needed for cell division.
Protein needed-microtubules
If DNA replication didn’t occur correctly, the cell cycle can be stopped here.
The cell grows in preparation for cell division
There are two important G stage controls. Where in interphase do they occur? How is this related to apoptosis?
During G1, the cell recovers from the previous division.
-The cell grows in size, increases the number of organelles (mitochondria and ribosomes)
-accumulates materials that will be used for DNA synthesis.
G2, the cell synthesized proteins that are needed for cell division like microtubules
-spindle fibers are microtubules that were made from the centrosome
-G2 checkpoint: if DNA replication didn’t occur correctly, the cell cycle stops here
Apoptosis: programmed cell death
- necessary for development so the body can reorganize the shape of the tissue
-allows the cell to fragment into the membrane-bound pieces that are less dangerous to organisms and easier to clean up
What is apoptosis?
Programmed cell death
- necessary for development so the body can reorganize the shape of the tissue
- allows the cell to fragment into the membrane-bound pieces that are less dangerous to organisms and easier to clean up
What do tumor suppressor proteins do in general?
- proteins coded for directly
- inhabits the cell cycle
- if mutated cell division unchecked
Are tumor suppressor proteins normal or do they only occur in cancer?
-tumor suppressor proteins are genes of cancer
How are tumor suppressor proteins related to the control points?
.
Name two tumor suppressor proteins.
RB and p53 genes that code for the RB and p53 proteins.
What is chromatin?
- Chromatin is a mass of genetic material composed of DNA and proteins that condenses to form chromosomes during eukaryotic cell division.
- Chromatin is located in the nucleus of our cells.
Is chromatin euchromatin or heterochromatin?
both
- euchromatin is loosely coiled DNA and some organizational proteins
- heterochromatin i during s phase, the double-stranded DNA replicates and the chromatin condenses to become tightly coiled DNA
Is chromatin generally active?
Loosely coiled euchromatin represents the active chromatin
What are histones and how are they used to organize DNA?
Histones- proteins that form a core for DNA to wrap around
- when DNA is wrapped around the core, it’s called nucleoside
- histones can be modified to change how genes can be used or be unavailable for use.
How are chromosomes made from DNA and histones? Is this euchromatin or heterochromatin?
- In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
- heterochromatin:highly compacted and not generally active
Is heterochromatin generally active?
-heterochromatin is highly compacted and not generally active
During which stage of mitosis is chromatin organized into chromosomes?
Prophase
Where is the centromere on a chromosome?
- The region that joins the two sister chromatids, or each half of the chromosome.
- In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers.
How are sister chromatin related?
A chromatid is formed during meiosis and is one of two identical DNA strands formed after DNA synthesis. Sister chromatids are from the same chromosome, and they are connected together at the centromere.
Where are the kinetochores a chromosome?
The kinetochores of each chromatin is attached to a spindle fiber.
What is the purpose of kinetochores?
a specialized condensed region of each chromosome that appears during mitosis surrounding centromere where the chromatids are held together to form an X shape
What is a Microtubule Organizing Center (MTOC)?
structure found in eukaryotic cells from which microtubules emerge.
MTOCs have two main functions:
-the organization of eukaryotic flagella and cilia
-the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division.
What are centrioles?
- a cylindrical organelle near the nucleus in animal cells.
- occurring in pairs and involved in the development of spindle fibers in cell division.
Are centrioles made of microtubules?
Centrioles are an organelle inside animal cells that are made of microtubules