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Cell Cycle Flashcards

1
Q

What is binary fission?

A

A form of asexual reproduction (a method of reproduction that produces genetically identical cells without sex cells)

Binary fission is characteristic of bacteria and involves several steps including DNA replication, elongation, and cell separation.

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2
Q

What are the three main reasons cells replicate?

A
  1. To survive
  2. To grow
  3. To reproduce

Cell replication is essential for maintaining life processes.

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3
Q

How is cell replication calculated?

A

C = 2^n (C = no. of cells, n = no. of divisions)

This formula illustrates exponential growth in cell replication.

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4
Q

What happens during the DNA replication step of binary fission?

A

Circular chromosome is uncoiled and replicated, including plasmids.

This step is crucial for ensuring both daughter cells receive genetic material.

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5
Q

What occurs during the elongation step of binary fission?

A

the cell stretches and the duplicated DNA migrates to opposite ends of the replicating cell.

This step prepares the cell for division.

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6
Q

Describe the cytokinesis step in binary fission.

A

The cell undergoes cytokinesis by pinching inwards and creating a septum.

This leads to the physical separation of the two new cells.

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7
Q

What is interphase in the eukaryotic cell cycle?

A

The first and longest stage where cellular growth and duplication of chromosomes occur, including G1, S, and G2 phases.

Interphase is critical for preparing the cell for mitosis.

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8
Q

What occurs during the G1 phase of interphase?

A

Cell growth
protein synthesis for DNA replication
organelle replication occur
volume of cytosol increasing.

At the end of G1, the cell may enter G0 if it does not need to replicate.

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9
Q

What is the purpose of the G0 phase?

A

Cells that are not required to replicate rest in this phase, which can be quiescent or terminally differentiated.

Quiescent cells can re-enter the cell cycle, while terminally differentiated cells cannot.

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10
Q

What happens during the S phase of interphase?

A

DNA replication
1 chromosome turns into 2 identical sister chromatids (held together by centromere)

Sister chromatids are held together by a centromere.

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11
Q

What are the four sub-stages of mitosis?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase

Each sub-stage has specific processes that ensure proper division of genetic material.

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12
Q

What occurs during prophase?

A

Chromatin condenses forming distinct chromosomes (visible under microscope)
Spindle fibers begin to form
Centrioles migrate to opposite ends of cell
Nuclear membrane breaks down and disappears.

This stage prepares the cell for alignment of chromosomes.

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13
Q

What is the role of spindle fibers during metaphase?

A

Spindle fibers fully form (attach to centromere of each sister chromatid)
Chromosomes align along the equator of cell

Proper alignment is crucial for accurate chromosome separation.

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14
Q

What occurs during anaphase?

A

Spindle fibers contract splitting the centromere
sister chromatids are pulled to opposite ends of cell. Geavage furrow prepares to form at center of cell (prepares to divide)

This stage is critical for ensuring each daughter cell receives the correct number of chromosomes.

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15
Q

What happens during telophase?

A

Spindle fibers disintegrate. Chromosomes condense together at either end of cell.
2 new nuclear membranes from producing 2 genetically identical nuclei. (basically reverse of Prophase)

Telophase is essentially the reverse of prophase.

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16
Q

How does cytokinesis differ in animal and plant cells?

A

In animals, a cleavage furrow develops; in plants, a cell plate forms before separation.

This distinction is due to the presence of a rigid cell wall in plant cells.

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17
Q

What is apoptosis?

A

Controlled programmed cell death occurring when a cell malfunctions, is damaged, or unnecessary.

Apoptosis is critical for maintaining healthy tissue and removing potentially harmful cells.

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18
Q

What are the two pathways of apoptosis?

A
  1. Mitochondrial pathway (intrinsic)
  2. Death receptor pathway (extrinsic)

Each pathway activates caspases to initiate cell death.

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19
Q

What is the role of caspase enzymes in apoptosis?

A

Caspases are activated to cause cell death by breaking down organelles and shrinking the cell.

They play a central role in the execution phase of apoptosis.

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20
Q

What defines benign tumors?

A

Slow-growing masses that do not spread to other tissues and organs.

Benign tumors are generally not life-threatening.

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21
Q

What characterizes malignant tumors?

A

abnormal Cells that invade nearby tissues and other parts of the body; these cells are cancerous.

Malignant tumors can be aggressive and life-threatening.

22
Q

What is the definition of totipotent stem cells?

A

Stem cells that can differentiate into any cell type, including those needed to form an entire organism.

A zygote is an example of a totipotent stem cell.

23
Q

What is the significance of the G1 and G2 checkpoints?

A

These checkpoints inspect for errors before the cell proceeds to the next stage of the cell cycle.

If errors are detected, repair mechanisms or apoptosis may be initiated.

24
Q

What is the consequence of decreased apoptosis?

A

It can result in the formation of tumors due to the unchecked replication of damaged cells.

This is often seen in cancerous cells.

25
How does excessive apoptosis affect the body?
Makes healthy cells die causig diseases such as Huntington's disease, Alzheimer's disease, and Parkinson's disease. ## Footnote Excessive loss of neurons can result in cognitive and motor function decline.
26
What are tumour suppressing genes?
Genes that help prevent uncontrolled cell growth and cancer ## Footnote Tumour suppressing genes play a critical role in regulating the cell cycle and promoting apoptosis.
27
Name a chemical factor that contributes to cancer.
Tobacco ## Footnote Tobacco contains numerous carcinogenic substances that can lead to various types of cancer.
28
What are physical factors that can cause cancer?
X-rays and UV rays ## Footnote These physical factors can cause DNA damage leading to cancerous changes in cells.
29
What are biological factors that can lead to cancer?
Viruses which cause cancer ## Footnote Certain viruses, like HPV and Hepatitis B, are known to increase cancer risk.
30
What are stem cells?
Undifferentiated cells with the capability of differentiating into specialised cells ## Footnote Stem cells are crucial for growth, repair, and regeneration in the body.
31
What is a zygote?
The fertilised egg that can differentiate into any cell type required to produce a foetus ## Footnote The zygote represents the earliest stage of development.
32
Define totipotent stem cells.
Stem cells that can differentiate into multiple cell types ## Footnote Totipotent stem cells can give rise to all cell types including those of the placenta.
33
What are embryonic stem cells capable of differentiating into?
Three germ layers: mesoderm, ectoderm, endoderm ## Footnote These layers will develop into different tissue types in the body.
34
Define pluripotent stem cells.
Stem cells that can differentiate into a limited number of cell types ## Footnote Pluripotent stem cells are derived from the inner cell mass of a blastocyst.
35
What types of cells can stem cells in the bone marrow differentiate into?
Types of blood cells: red, white, and platelets ## Footnote Bone marrow stem cells are essential for the production of blood.
36
What is the morula?
A solid ball of cells formed after a fertilised egg undergoes mitotic divisions ## Footnote The morula stage occurs before the formation of the blastocyst.
37
What happens to the morula after it consists of 16 cells?
It enters the uterus ## Footnote This is a critical step in the development of the embryo.
38
What is the blastocyst?
A structure containing an inner mass of cells surrounded by an outer layer ## Footnote The blastocyst stage is crucial for implantation in the uterine wall.
39
What does the inner layer of the blastocyst form?
Tissues of the embryo ## Footnote This inner mass will develop into various organs and systems.
40
What does the outer layer of the blastocyst form?
The placenta ## Footnote The placenta is vital for nutrient and waste exchange between the mother and embryo.
41
What forms after implantation of the blastocyst into the uterine wall?
Gastrula ## Footnote The gastrula stage marks the beginning of the formation of germ layers.
42
What are the three germ layers formed during embryo development?
Ectoderm, mesoderm, endoderm ## Footnote These layers give rise to different tissues and organs in the developing embryo.
43
What does the ectoderm form?
Skin, hair, nervous system, eyes ## Footnote The ectoderm is the outermost germ layer.
44
What does the mesoderm form?
Muscles, cartilage, blood, bones ## Footnote The mesoderm is the middle germ layer.
45
What does the endoderm form?
Lungs, digestive system, bladder, and other organs ## Footnote The endoderm is the innermost germ layer.
46
What type of cells undergo mitosis?
Somatic cells (non sex cells)
47
Purpose of Apoptosis
Remove damaged cells (cencerous/infected) sculpt body to final form (remove unecsessary skin) EG. Wbbing between figers and eyelids.
48
Factors affecting Apoptosis
Mutation in genes inherited mutated genes chemical factors physical factors biological factors
49
What Necrosis
It is another way cells die (unregulated death of cell to swell and burst releasing call contents into surrounding enviroment) Necrosis can spread to neibouring tissues as damaged cells bursting and releasing its contents may lead to inflammation and damage nearby cells.
50
Mitochondrial Pathway (intrinsic)
initiated by reception of extracellular death signaling molecules. When cell is stressed or DNA is damaged mitochondria detects this and releases cytochrome C. This binds with proteins to activate capase enymes. When capase enzymes active apoptoisis begins.
51
Death Receptor (entrinsic)
occurs due to infection in cancer/infected cells. death signaling molecules from the external immune cell bind to death receptor proteins on the PM. Also causes capase to actiate, apoptosis begins.

Biology (4 decks)

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