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Ch 12 Flashcards

1
Q

Each chromatid is connected in the center by a _____________.

A

centromere

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2
Q

Describe Chromatin

A

In eukaryotic cells, DNA wraps around histone proteins. This forms chromatin which is loose/ accessible DNA.

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3
Q

Describe Cytokinesis

A

Cytoplasm divides forming 2 distinct cells.

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4
Q

Describe each part of the cell cycle.

A

The cell cycle includes interphase stages: G₁ (growth, producing proteins and organelles), S (DNA synthesis and more growth), and G₂ (growth and preparation for division, checking DNA for errors), Mitosis (nucleus divides), and Cytokinesis (cytoplasm divides).

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5
Q

Relationship between surface area and volume as a cell increases in size.

A

As a cell increases in size, its numerator is the cell’s surface area^2 (squared), while its denominator is the cell’s volume^3 (cubed).

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6
Q

Importance of volume vs surface area of a cell

A

Volume: Enzyme/chemical reactions occur here (supplies used).
Surface Area: How materials get into/out of cells.

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7
Q

Role of H1 histone in chromatin structure.

A

H1 histone holds the nucleosome “beads” together to increase compaction further.

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8
Q

Why do multicellular organisms make more cells?

A

Cell size is limited by its surface area to volume ratio (SA:V). If a cell gets too large, it isn’t possible for it to get oxygen/nutrients in and wastes out by diffusion.

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9
Q

Importance of nucleus division

A
  • Stores DNA (information of life) - All new cells need this information
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10
Q

Describe Mitosis

A

About 10% of cell cycle, Nucleus divides into 2 nuclei, each with the same number and kind of chromosomes (DNA) as the parent cell.

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11
Q

relationship between chromatin and chromosome

A

Chromatin further coils and condenses to form a chromosome.

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12
Q

Describe the nucleosome structure.

A

DNA wraps around 8 histone proteins, is stabilized by the H1 histone protein, forming a nucleosome,

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13
Q

After the S phase of Interphase, each chromosome consists of ________________________.

A

two sister chromatids (these are the two identical halves of a duplicated chromosome).

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14
Q

Meaning of growth of a multicellular organism in terms of the cells

A

Made up of more cells due to cell division (not larger cells)

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15
Q

How chromatin coils tightly.

A

Chromatin wraps around 8 histone proteins.

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16
Q

Describe G₁ phase

A

Growth phase where the cell produces proteins and organelles.

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17
Q

Describe a chromosome.

A

A duplicated chromosome consists of two chromatids joined by a centromere. The kinetochore is the structure where spindle fibers attach during cell division.

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18
Q

Purpose of mitosis

A
  • Growth and repair of an organism - Grow from an embryo to an adult - Repair damaged tissues - Replaces worn out cells
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19
Q

Describe the function of nucleosomes.

A

Nucleosomes aide in the compaction of the chromosome.

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20
Q

Describe Interphase

A

Longest stage (90%) of cell cycle; preparation for cell division; cell is doing its normal function/job (e.g., making proteins), also copying its DNA.

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21
Q

What is a diploid cell?

A

Diploid cells have two complete sets of chromosomes, one from each parent.

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22
Q

What happens to the nuclear envelope in telophase?

A

A new nuclear envelope forms around the chromatin as vesicles fuse back together.

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23
Q

How does a cell plate form in cytokinesis in plant cells?

A

Membrane-bound vesicles contribute to forming the new cell wall.

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24
Q

In animal cells, what structure pinches the cell membrane to divide the cell?

A

Ring of contractile protein

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25
Describe what is happening to the DNA in prophase.
During prophase, chromatin condenses, making chromosomes visible under a microscope.
26
Describe cytokinesis in plant cells.
Cytokinesis in plant cells involves the formation of a cell plate. A cell plate forms as vesicles carry new cell wall material to the center of the cell.
27
Describe the Formation of Spindle Fibers
Spindle fibers form from Microtubule Organizing Centers (MTOC) during prophase. These fibers are made of microtubules.
28
How do the spindle fibers shorten in anaphase?
Microtubule motor breaks down tubulin proteins, causing chromosomes to move using ATP.
29
What happens to the chromosomes in telophase?
During telophase, chromosomes uncoil back into chromatin.
30
Describe Metaphase
Spindle fibers move chromosomes and line them up in the center of the cell (metaphase plate).
31
What happens to the nucleus in prophase?
Nuclear envelope breaks down into vesicles in late prophase.
32
Describe what a kinetochore is.
The kinetochore is a protein structure on chromatids where the spindle fibers attach during cell division to pull sister chromatids apart.
33
What happens to the spindle apparatus in telophase?
The spindle breaks apart during telophase.
34
What is the indent called that forms during cytokinesis in animal cells?
Cleavage furrow
35
Function of Kinetochore
The fibers connect from the poles of the spindle to the kinetochore of each centromere for every chromosome.
36
Describe what is happening with the Centrosomes and Centrioles Movement in prophase.
Centrosomes (Microtubule Organizing Centers) and centrioles separate and start to move to opposite sides of the nucleus during prophase.
37
What happens with the spindle fibers in prophase?
Spindle fibers move towards centromeres of chromosomes and attach during prophase.
38
What happens to the nucleolus in telophase?
The nucleolus reappears/ reforms in each new nucleus during telophase.
39
Primary tumors vs secondary tumors
Primary tumor- Original tumor at original site Secondary tumor- Pieces of a tumor may spread to other parts of the body and anchor in that new location. These new tumors are secondary tumors.
40
Immune system's role in abnormal cells
The immune system's role is to identify and eliminate cells that have undergone transformation or mutation and are growing in an abnormal manner.
41
Importance of mitotic index in cancer treatment
The mitotic index is used for predicting the response of cancer cells to chemotherapy. We want mitotic index to be going down after treatment has begun.
42
Role of Checkpoints in the Cell Cycle
Checkpoints in the cell cycle hold cells until it is appropriate to progress to the next phase and ensure cells stop dividing.
43
2 Types of physical factors that regulate the cell cycle
1. Density-dependent inhibition 2. Anchorage dependence
44
State the two groups of genes can change a normal cell into a tumor cell if they mutate.
1) proto-oncogenes 2) tumor suppressor genes
45
Describe how Growth factors are crucial for cell division.
Specific regulatory substances called growth factors are necessary for most cells to divide. Cyclins are a family of proteins that control the progression of a cell through the cell cycle.
46
Properties of malignant tumors
- Excessive cell proliferation (lost density dependent inhibition) (Note that benign tumors also display this property) - May have unusual numbers of chromosomes - May have abnormal metabolism - Abnormal cell surface changes (lost attachments to neighboring cells/lost anchorage dependence)
47
Examples of Chemical Mutagens
- cigarette smoke - chewing tobacco - DDT (insecticide) - pollution -chromium-6(heavy metal)
48
Radiation
Gamma rays are used for radiation treatment targeting tumors.
49
Explain how Cancer cells do not respond to the body's control mechanisms.
Cancer cells can divide excessively, invade other tissues, and can kill the organism if left unchecked. -They may make their own growth factors -They have their own signaling system -They divide indefinitely
50
Mitotic index definition
The mitotic index is the ratio between the number of cells in mitosis in a tissue and the total number of observed cells.
51
describe Malignant tumors
Malignant tumors invade other tissues or organs. Malignant tumors are cancerous and can spread.
52
Proto-oncogenes function.
Proto-oncogenes help cells divide and are essential for cell growth and division. They are like the gas pedal on a car.
53
Treatments for tumors
- Surgery (for benign tumors) - Radiation - Chemotherapy
54
Describe how Essential nutrients are necessary for cell division.
If essential nutrients are left out of the culture medium, cells will not divide. Glucose is an example of a nutrient.
55
Tumor-suppressor genes function
prevent cell proliferation by acting as brakes at checkpoints in the cycle or by causing cells with too much damage to self destruct (apoptosis)
56
Threshold Concentration of Cyclins
Unless a specific cyclin reaches a threshold concentration, the cell cannot proceed to the next step in the cell cycle.
57
2 Categories of External factors influencing cell division
1. Chemical factors 2. Physical factors
58
Chemotherapy
Chemotherapy involves using drugs to kill cancer cells.
59
Benign tumors.
Benign tumors remain at the original tumor site and can be completely removed by surgery. The are superficial (non-invasive). Benign tumors are non-cancerous growths.
60
Proto-oncogenes can mutate into ____________, which actively promote cell proliferation.
Oncogenes (this is like slamming on the gas pedal in a car and not letting off)
61
Examples of High Energy Radiation Mutagens
sun (UV rays), nuclear waste, x-rays
62
Mitotic index formula
(# cells in mitosis) / (total # of cells in the sample) x 100
63
Cancer cells behavior
Cancer cells are abnormal and do not exhibit density-dependent inhibition, and some don’t have anchorage-dependent inhibition.
64
Metastasis
The process by which cancer cells separate from the original tumor, spread into other tissues, enter the blood and lymph vessels, and develop into new tumors (secondary tumors).
65
Anchorage dependence in animal cells
Many animal cells exhibit anchorage dependence, meaning they must adhere to a substratum, such as the surface of a culture dish or the extracellular matrix of a tissue.
66
MUTAGENS
Factors which can cause an “alteration of genes” which are mutations
67
True/ False: Tumor-suppressor genes usually need both versions of these genes to be mutated to eliminate the “brakes”
True
68
Density-dependent inhibition
Crowding inhibits cell division. Cells stop dividing when they form a complete single layer.
69
Common property of all tumors
Excessive cell proliferation
70
Adult Stem Cell Niches
Microenvironment with conditions needed for stem cells to remain inactive and dormant until needed, then rapidly proliferate and differentiate into functioning cells.
71
totipotent
can become any type of cell that can create an entire organism. Example: ball of cells before embryo stage.
72
Adult Stem Cells (ASC) locations
Found in the blood, bone marrow, liver, kidney, cornea, dental pulp, umbilical cord, brain, skin, muscle, salivary gland.
73
Unipotent
can only form one type of cell. Example: germ line making sperm cells or skin cells.
74
pluripotent
can become any type of cell of the organism but can’t create the organism itself. Example: Embryonic Stem Cells (ESC).
75
Potential of stem cell therapy
- Regenerate tissues/organs - Cure diseases like diabetes, multiple sclerosis, etc.
76
Function of Adult Stem Cells
Repair system for the body, replenishing specialized cells, and maintaining the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.
77
Stem cells are extraordinary because they can....
divide and make identical copies of themselves through mitotic cell division (Self-Renewal) and have the potential to differentiate into a diverse range of specialized cell types (Potency).
78
Process of in vitro fertilization and development of pluripotent stem cells.
In vitro fertilization involves combining sperm and egg outside the body to create a fertilized egg. This develops into a morula and then a blastocyst. The inner cell mass is removed to obtain pluripotent stem cells, which can differentiate into various cell types like skin, pancreatic, and nerve cells. These cells can be transplanted into patients.
79
Skeletal Muscle Stem Cells
Remain inactive unless there is muscle injury; after injury, the niche environment changes, and cells proliferate to replace damaged muscle tissue.
80
Why is stem cell research important?
-Stem cells allow us to study how organisms grow and develop over time. -We can test different substances (drugs and chemicals) on stem cells. -We can get a better understanding of our “genetic machinery.” -Stem cells can replace diseased or damaged cells that can not heal or renew themselves.
81
Multipotent
can become more than one cell type within a specific subset. Example: bone marrow stem cells and umbilical cord blood cells.
82
What is the purple bundle of cells called? What type of stems cells do we gain from this?
Blastocyst; embryonic stem cells (pluripotent)
83
Diseases currently being treated with stem cells
- Parkinson’s Disease - Leukemia (Bone Marrow Transplants) - Skin Grafts from severe burns - Stargardt's disease (improvement in vision)
84
Embryonic Stem Cells (ESC) origin
From blastocysts left over from In-Vitro Fertilization (IVF) in the laboratory and from aborted fetuses.

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