Cell Cycles Flashcards
What is the result of cell metabolism that can be observed?
Cell growth
Cell metabolism itself is not easily visible, but its effects can be seen in the growth of cells.
What happens when cells reach a certain size?
They split in two
Cells cannot grow indefinitely and must divide to form new cells.
How does growth vary among different organisms and tissues?
It varies widely
Different organisms, organs, and tissues have different rates and patterns of growth.
How often are intestinal cells replaced in adult humans?
Every few days
Intestinal cells have a high turnover rate compared to other cell types.
How often are skin cells replaced in adult humans?
Every few weeks
Skin cells have a moderate turnover rate.
Under what condition do liver cells grow and divide rapidly?
When they are damaged
Liver cells typically do not divide unless necessary for repair.
Do human nerve cells frequently divide?
Seldom
Nerve cells have very limited capacity for division.
What does cell theory state about living things?
All living things are composed of cells
Additionally, cells must arise from other cells.
What is a parent cell often referred to as?
Mother cell
The parent cell divides to form daughter cells.
What are the new cells formed from a parent cell called?
Daughter cells
These cells result from the division of the mother cell.
What is the process of growth, division, and growth called?
Cell cycle
The cell cycle is a regulated process ensuring proper cell numbers and locations.
True or False: The cell cycle is an unregulated process.
False
The cell cycle is a highly regulated process.
Fill in the blank: The cell cycle ensures that organisms have the right number of cells in the right _______.
Places
This includes tissues, organs, and systems.
What are the two types of cell division in eukaryotes capable of sexual reproduction?
Mitosis and meiosis
Mitosis results in identical daughter cells, while meiosis produces specialized sex cells.
What type of cells does mitosis produce?
Identical daughter cells
Mitosis is used by somatic cells to make more body cells.
What are somatic cells?
Body cells
These are the cells that undergo mitosis for growth and repair.
What type of cells does meiosis produce?
Sex cells or gametes
These cells are specialized for sexual reproduction.
What is unique about the chromosome number in gametes produced by meiosis?
They have only half a set of chromosomes
This reduction is essential for maintaining the chromosome number in the resulting organism.
Fill in the blank: Mitosis results in _______ daughter cells.
identical
This is crucial for growth and tissue repair.
True or False: Meiosis results in daughter cells that are identical to the parent cell.
False
Meiosis produces genetically diverse gametes.
What is the role of gametes in sexual reproduction?
To fuse with another gamete to form a new individual
This fusion is essential for the development of a new organism.
What is the primary purpose of mitosis in organisms?
To increase the number of cells, enabling growth and repair of tissues
Mitosis allows organisms to grow from a single cell to a complex multicellular organism.
How do cells in the body constantly renew themselves?
Through mitosis, which replaces lost cells with new ones
This process is particularly evident in the skin and gut.
What is the lifespan of red blood cells, and how are they replaced?
Red blood cells live for four months and are replaced by mitosis
Mitosis ensures a continuous supply of red blood cells.
What role does mitosis play in the growth of organisms?
It allows for growth and the repair of damaged tissues
Mitosis is essential for maintaining healthy tissue.
What is budding in relation to mitosis?
A process where some organisms produce genetically identical offspring through mitosis
This method is notably used by organisms like the hydra.
What type of reproduction do yeast cells utilize?
Asexual reproduction through mitosis
Yeast cells multiply by this method.
Fill in the blank: Mitosis is important for organisms to grow and repair _______.
damaged tissues
True or False: Mitosis is only involved in the growth of multicellular organisms.
False
Mitosis is also involved in asexual reproduction and cell replacement.
What are chromosomes?
Structures made of DNA and proteins that carry hereditary information of cells
Chromosomes are essential for the proper distribution of genetic material during cell division.
What do chromosomes carry?
The DNA code to build all the cell’s proteins
This genetic information is crucial for the functioning and replication of cells.
Where does DNA exist in a cell during interphase?
In the nucleus as a loose mass of DNA threads and proteins called the chromatin network
The chromatin network is less organized and allows for gene expression and replication.
What happens to the chromatin network when a cell prepares to divide?
It condenses, thickens, and becomes visible as short thick chromosomes under a light microscope
This process is essential for ensuring that DNA is accurately divided between daughter cells.
True or False: Chromosomes are only visible during cell division.
True
Chromosomes are not visible in their condensed form during the interphase of the cell cycle.
Fill in the blank: The DNA is packaged in chromosomes so that it can be _______ between each daughter cell.
distributed
Proper distribution of DNA is critical for maintaining genetic integrity in daughter cells.
What is the process of DNA replication?
The process by which DNA in the nucleus is duplicated to ensure each daughter cell receives the same DNA copy as the mother cell.
DNA replication is crucial for cell division and genetic continuity.
What are chromatids?
Identical parts of a replicated chromosome that result from DNA replication.
Each replicated chromosome consists of two chromatids.
What is a replicated chromosome?
A chromosome that consists of two identical parts called chromatids after DNA replication.
The term ‘replicated chromosome’ is used to describe the chromosome post-replication.
What is a centromere?
The structure that visibly joins the two chromatids of each replicated chromosome during cell division.
The centromere plays a key role in the separation of sister chromatids during mitosis.
What are sister chromatids?
The two identical chromatids on a replicated chromosome.
Sister chromatids are separated during mitosis to ensure each daughter cell receives the correct genetic material.
During which phase are sister chromatids separated?
Mitosis.
Mitosis is the process of cell division that results in two identical daughter cells.
What is the main function of the centrosome?
The main microtubule organizing center of the animal cell and a regulator of cell cycles
The centrosome plays a crucial role in maintaining the structure of the cell.
What is the structure of a centrosome?
Made up of two centrioles sitting at right angles to each other
Centrioles are cylindrical structures that are essential for cell division.
What happens to the centriole before cell division?
The centriole duplicates so that each daughter cell receives one
This duplication is critical for the proper functioning of the centrosome in the daughter cells.
What structure does the centrosome organize during cell division?
The spindle apparatus
The spindle apparatus is composed of spindle fibres (microtubules) that help segregate chromosomes.
Fill in the blank: The centrosome is crucial for providing _____ for the cell.
Structure
The centrosome contributes to the overall framework of the cell known as the cytoskeleton.
True or False: The centrosome is only involved in the organization of microtubules.
False
The centrosome also regulates cell cycles.
What is the basic pattern of growth and division in somatic cells called?
The cell cycle
The cell cycle includes both the mitotic phase and interphase.
What is the brief portion of the cell cycle where actual cell division occurs?
The mitotic phase
This phase is commonly referred to as mitosis.
What is the term for the rest of the cell cycle between two mitotic phases?
Interphase
Interphase is where the cell grows and prepares for division.
What are the three parts of interphase?
- G1-phase
- S-phase
- G2-phase
Each phase has distinct functions in the cell cycle.
What happens during the G1-phase of interphase?
The new cell grows and carries out its normal cell duties
Some cells may remain in G1-phase for their entire life.
What is the S-phase responsible for in the cell cycle?
DNA synthesis
If a cell is going to divide, it progresses from G1-phase to S-phase.
True or False: Some specialized cells, like nerve cells, remain in the G1-phase for their entire lives.
True
These cells do not proceed to division.
Fill in the blank: The second growth phase of interphase is called the _______.
G2-phase
This phase follows the S-phase.
What occurs during the S-phase of interphase?
DNA replication takes place
This process ensures that each daughter cell receives a complete copy of the parent’s genetic material.
What happens to the chromosomes during the S-phase?
All chromosomes are copied
This is essential for genetic continuity in daughter cells.
What is duplicated alongside chromosomes during the S-phase?
The centrioles of the centrosome
This duplication is crucial for proper cell division.
What phase follows the S-phase in interphase?
G2-phase
During the G2-phase, the cell continues to grow and prepare for division.
What occurs during the S-phase of interphase?
DNA replication takes place
This process ensures that each daughter cell receives a complete copy of the parent’s genetic material.
What happens to the chromosomes during the S-phase?
All chromosomes are copied
This is essential for genetic continuity in daughter cells.
What is duplicated alongside chromosomes during the S-phase?
The centrioles of the centrosome
This duplication is crucial for proper cell division.
What phase follows the S-phase in interphase?
G2-phase
During the G2-phase, the cell continues to grow and prepare for division.
What is the name given to the process where the nucleus and chromosomes are divided during mitosis?
Karyokinesis
Karyokinesis is a critical part of cell division, ensuring that each daughter cell receives an identical set of chromosomes.
List the four continuous phases of mitosis.
- Prophase
- Metaphase
- Anaphase
- Telophase
Each phase plays a distinct role in the process of cell division.
What is the name of the process where the cytoplasm, organelles, and cell membrane are divided?
Cytokinesis
Cytokinesis occurs towards the end of mitosis and is essential for the formation of two separate daughter cells.
True or False: Cytokinesis occurs before karyokinesis during mitosis.
False
Karyokinesis occurs first, followed by cytokinesis.
Fill in the blank: The four phases of mitosis are Prophase, Metaphase, Anaphase, and _______.
Telophase
Telophase is the final stage of mitosis before cytokinesis.
What occurs during prophase?
The chromatin network condenses to form visible chromosomes with chromatids, the nuclear membrane and nucleolus disappear, centrioles move to opposite sides of the cell, and spindle fibres form between the centrioles.
What happens to the nuclear membrane during prophase?
It disappears.
What structural component forms between the centrioles during prophase?
Spindle fibres.
What is the configuration of chromosomes during prophase?
Visible chromosomes with two sister chromatids each.
What is the position of chromosomes during metaphase?
They line up on the equator (mid-line) between the poles.
What attaches to the centromeres on each chromosome during metaphase?
Spindle fibres.
Fill in the blank: During prophase, the centrioles move towards _______.
opposite sides of the cell.
True or False: The nucleolus remains intact during prophase.
False.
What are the two main processes occurring in prophase?
- Chromatin condensation into chromosomes
- Disappearance of nuclear membrane and nucleolus
How many replicated chromosomes are shown in the prophase model?
Four.
What happens during anaphase?
The centromere of each chromosome divides and the two chromatids split apart. Unreplicated chromosomes move to opposite poles. Cytokinesis typically begins.
What is the main event that occurs during telophase?
The unreplicated chromosomes reach the poles and the nuclear membrane and nucleolus form around them.
What happens to the spindle during telophase?
The spindle disappears.
What occurs during cytokinesis in animal cells?
Cell cleavage occurs.
What forms during cytokinesis in plant cells?
A cell plate forms at the equator.
Fill in the blank: During anaphase, the _______ of each chromosome divides.
[centromere]
True or False: Cytokinesis begins during anaphase.
True
Fill in the blank: The unreplicated chromosomes are at the _______ during telophase.
[poles]
What is cytokinesis?
The process required to divide the cytoplasm after karyokinesis.
During which phases does cytokinesis usually begin?
Anaphase or telophase.
How does cytokinesis occur in animal cells?
A ring of filaments contracts around the center of the dividing cell, pinching it in half.
What do daughter cells receive during cytokinesis in animal cells?
About half of the cell membrane and cytoplasm, including organelles like mitochondria.
How do plant cells perform cytokinesis?
A cell plate forms along the equator between the two daughter nuclei.
What eventually forms between the daughter cells in plant cytokinesis?
A new cell wall.
True or False: Cytokinesis and karyokinesis are the same processes.
False.
Fill in the blank: In animal cells, cytokinesis involves a ring of _______ that pinches the cell.
filaments
What is the role of the cell plate in plant cells during cytokinesis?
It helps separate the two daughter nuclei by forming a new cell wall.
What is cancer?
A disease caused by an uncontrolled division of abnormal cells in a part of the body
Cancer cells lose their original function.
What is formed after repeated division of abnormal cells?
A tissue mass called a tumour
Tumours can be benign or malignant.
How are cancers typically named?
According to the organ where they originate
For example, lung cancer originates in the lung.
Fill in the blank: Cancer is caused by _______ of abnormal cells.
uncontrolled division
True or False: All tumours are cancerous.
False
Tumours can be benign (non-cancerous) or malignant (cancerous).
What is cancer?
A disease caused by an uncontrolled division of abnormal cells in a part of the body
Cancer cells lose their original function.
What is formed after repeated division of abnormal cells?
A tissue mass called a tumour
Tumours can be benign or malignant.
How are cancers typically named?
According to the organ where they originate
For example, lung cancer originates in the lung.
Fill in the blank: Cancer is caused by _______ of abnormal cells.
uncontrolled division
True or False: All tumours are cancerous.
False
Tumours can be benign (non-cancerous) or malignant (cancerous).
What defines benign tumours?
Do not penetrate surrounding tissues and are usually enclosed in a capsule
Benign tumours typically grow slowly and do not metastasize.
How do benign tumours usually grow?
Quite slowly
Unlike malignant tumours, benign tumours do not spread to other parts of the body.
What is a common characteristic of benign tumours in terms of their structure?
Covered by normal cells
This covering is made up of cells that are similar to normal cells.
What are some problems associated with benign tumours?
If they:
* Grow very large
* Become uncomfortable or painful
* Are visible and unpleasant
* Press on other body organs
* Release hormones affecting the body
These factors may necessitate medical intervention.
What characterizes malignant tumours?
Spread between the cells of the tissues, damaging them
Malignant tumours typically grow faster than benign tumours.
How do malignant tumours differ in growth compared to benign tumours?
Grow faster
This rapid growth often leads to more severe health consequences.
What does metastasis refer to?
The spread of malignant tumours to other parts of the body
This process can lead to secondary tumours in different organs.
True or False: Benign tumours can metastasize.
False
Benign tumours do not spread to other parts of the body.
Fill in the blank: Malignant tumours cause damage by spreading into _______.
Surrounding tissues
This invasion leads to significant tissue damage.
