- 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.

- a cylindrical organelle near the nucleus in animal cells. - occurring in pairs and involved in the development of spindle fibers in cell division.

Ch 9 Flashcards by Jessica Stone

Name the three main stages on interphase.

G1
S
G2

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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

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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.

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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

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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

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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

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What do tumor suppressor proteins do in general?

proteins coded for directly
inhabits the cell cycle
if mutated cell division unchecked

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Are tumor suppressor proteins normal or do they only occur in cancer?

-tumor suppressor proteins are genes of cancer

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How are tumor suppressor proteins related to the control points?

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Name two tumor suppressor proteins.

RB and p53 genes that code for the RB and p53 proteins.

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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.

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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

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Is chromatin generally active?

Loosely coiled euchromatin represents the active chromatin

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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.

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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

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Is heterochromatin generally active?

-heterochromatin is highly compacted and not generally active

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During which stage of mitosis is chromatin organized into chromosomes?

Prophase

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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.

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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.

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Where are the kinetochores a chromosome?

The kinetochores of each chromatin is attached to a spindle fiber.

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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

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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.

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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.

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Are centrioles made of microtubules?

Centrioles are an organelle inside animal cells that are made of microtubules

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How many centrioles does it take to make a centrosome?

Two centrioles

How many centrosomes does a eukaryotic cell have?

Each centrosome in an animal cell contains a pair of barrel-shaped organelles called centrioles. Centrioles are not found in plant cells.

Are asters made of microtubules?

-ashters are array of short microtubules

Does the MTOC control the production of ashers?

Do ashers anchor the MTOC to the cell wall during cell division?

What are spindle fibers?

- protein structures that form early in mitosis or cell division. - they consist of microtubules that originate from centrioles

Are spindle fibers made of microtubules?

-yes they consist of microtubules that originate from centrioles.

Are spindle fibers produced by the MTOC?

What happens during prophase?

Early: -centrosomes have duplicated and begin to migrate to the poles of the cell -Chromatin is condensing to chromosomes -nuclear envelope is breaking into fragments Mid: -nucleolus disappears -centrosomes are closer to the poles -spindle fibers are forming Late: -pro metaphase -the kinetochores of each chromatid is attached to a spindle fiber -chromosomes are moving to the center of the cell

What is happening to the centrosomes in prophase?

Early-centrosomes have duplicated and begin to migrate to the poles of the cell Mid-centrosomes are closer to the poles

What is happening to the chromatin in prophase?

-chromatin is condensing to chromosomes

What is happening to the nuclear membrane in prophase?

- the nuclear envelope is breaking into fragments | - nucleolus disappears

What is happening to the nucleolus in prophase?

-the nucleolus disappears

What happens during pro-metaphase to the chromosomes?

-the chromosomes are moving to the center of the cell

What happens during metaphase?

- chromosomes align at the center of the cell- metaphase plate - centrosomes are at the poles of the cell

Where are the chromosomes in metaphase?

-chromosomes align at the center of the cell

What is the metaphase plate?

-chromosomes that are aligned at the center of the cell

What moved the chromosomes in metaphase?

What happens during anaphase?

-sister chromatids are separated at the centromere and are pulled to the opposite side of the cell

Does cytokinesis begin in anaphase?

-yes cytokinesis begins in anaphase

What happens during telophase?

- daughter cells are reforming the nuclear membrane - nucleoli reappear - chromosomes uncoil to become chromatin - opposite of prophase - cell gets ready for interphase activities

Why is telophase described as being just the opposite of prophase?

- because telophase the nucleoli reappears and in prophase it disaapears - in telophase chromosomes uncoil to become chromatin and in prophase chromatin is condensing to chromosomes - they do the exact opposite of each other

Is cytokinesis still continuing in telophase?

How are actin microfilaments involved in cytokinesis?

What is a cleavage furrow?

- cleavage furrow indents the plasma membrane between the. Two daughter nuclei - cleavage furrow deepens as band of actin filament constricts between the two daughter cells.

In plants, the Golgi apparatus produces vehicles that align at the metaphase. What do those vesicles contain?

- vesicles move between the daughter nuclei - vesicles fuse forming cell plate - their membranes complete plasma membranes of daughter cells - vesicles also release molecules that signal the formation of plant cell walls

In plants, the Golgi apparatus produces vehicles that align at the metaphase. What is being constructed?

In plants, the Golgi apparatus produces vehicles that align at the metaphase. What is the carbohydrate that is providing structure?

- walls are strengthened by the addition of cellulose fibrils and space between filled with middle lamella

Do stem cells retain the ability to go through the cell cycle?

-retain ability to divide and specialize

What is the stage called where most cells in adults stay and lose the ability to divide?

Stem Cells - retains ability to divide and specialize - adult: red bone marrow - embryonic * great potential for treating disease

Where do bacteria and archaea keep their DNA?

Where is the bacterial DNA anchored? How does this help each new bacteria get the right amount of DNA. After binary fission??

What are five characteristics of cancer?

1. Lack differentiation 2. Are immortal 3. Have abnormal nuclei 4. Don't unto apoptosis 5. Lack of contact inhibition 6. Are invasive 7. Undergo metagenesis and angiogenesis

Define proto-oncogene.

- A normal gene which, when altered by mutation, becomes an oncogene that can contribute to cancer. - may have many different functions in the cell. - provide signals that lead to cell division. - regulate programmed cell death (apoptosis).

Define tumor suppressor gene.

A tumor suppressor gene or antioncogene -a gene that protects a cell from one step on the path to cancer. -When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer.

Define telomere.

A compound structure at the end of a chromosome.

Define metastasis.

- Spreads new tumors distant from the primary tumor - These cells produce enzymes, allowing tumor cells to invade underlying tissues. Then, they travel through the blood and lymph, to start tumors elsewhere in the body.

Ch 9 Flashcards

(61 cards)