Unit 4 Test 2 Pt 1 Flashcards
What are feedback mechanisms?
Sensory pathways and responses that your body uses to maintain homeostasis.
Feedback mechanisms are essential for regulating various physiological processes.
What are the two types of feedback mechanisms?
- Negative Feedback
- Positive Feedback
These mechanisms play crucial roles in homeostatic regulation.
What does negative feedback do?
Slows down or stops a response.
Negative feedback is vital for maintaining stability in biological systems.
What does positive feedback do?
Amplifies or increases a response.
Positive feedback is often involved in processes that need a definitive outcome, such as childbirth.
What is an example of a stimulus in body temperature regulation?
Body temperature exceeds 37°C.
This triggers the feedback mechanism to restore normal temperature.
What type of sensors are involved in body temperature regulation?
Sensors like nerve cells with endings in the skin and brain.
These sensors detect changes in temperature and send signals to the control center.
What is the control center for body temperature regulation?
Temperature regulatory center in brain.
This center processes information from sensors and coordinates an appropriate response.
What is the effector in the negative feedback loop for body temperature regulation when the body becomes too hot?
Sweat glands throughout body.
Sweat glands help cool the body when temperature rises.
Fill in the blank: Negative feedback mechanisms tend to _______ a response.
[slow down or stop]
This action is crucial for maintaining homeostasis.
Fill in the blank: Positive feedback mechanisms tend to _______ a response.
[amplify or increase]
This is often seen in processes requiring a rapid change.
What is the function of negative feedback in physiological processes?
It regulates physiological processes by stopping a cellular response
This mechanism helps maintain homeostasis.
Give an example of negative feedback in the body.
Body temperature regulation through shivering and sweating
Shivering increases body temperature, while sweating decreases it.
What happens when body temperature increases in the context of negative feedback?
Stopping the response causes the body system to return to its normal state, a ‘set point’
This process helps to re-establish homeostasis.
True or False: Negative feedback mechanisms are responsible for initiating biological processes.
False
Positive feedback mechanisms are responsible for initiating and amplifying these processes.
Fill in the blank: Negative feedback mechanisms help to re-establish _______.
homeostasis
Homeostasis refers to the body’s ability to maintain a stable internal environment.
How can you describe negative feedback in simple terms?
Counteracting the effect of something
Or stop or slow down a response
Positive feedback leads to another response but doesn’t lead to _____ while negative feedback does
Homeostasis
What is the role of insulin in blood glucose regulation?
Insulin stimulates the uptake of glucose by target cells, reducing blood glucose levels
Insulin is secreted by the pancreas in response to increased blood glucose.
What happens when blood glucose levels increase?
Stimulates secretion of insulin from the pancreas
This is part of the negative feedback mechanism that helps maintain homeostasis.
How does insulin affect target cells?
Causes them to increase uptake of glucose for use or storage
This process reduces the levels of glucose in the blood.
What occurs when insulin decreases blood glucose levels?
There is no longer a stimulus to release insulin
This illustrates the negative feedback loop in glucose regulation.
Fill in the blank: An increase in blood glucose typically stimulates secretion of _______.
[insulin]
True or False: Insulin increases blood glucose levels.
False
Insulin decreases blood glucose levels by facilitating glucose uptake.
What is the role of negative feedback in maintaining homeostasis?
Negative feedback helps to maintain homeostasis by counteracting changes in the body.
What stimulates the secretion of glucagon?
A decrease in blood glucose.
Where is glucagon secreted from?
Pancreatic cells.
What effect does glucagon have on target cells, especially in the liver?
It causes the release of glucose through glycogen breakdown.
What happens to blood glucose levels when glucagon acts on the liver?
Blood glucose levels increase.
What occurs when blood glucose levels increase?
There is no longer a stimulus to release glucagon.
What are insulin and glucagon classified as?
Counter-regulatory hormones
What is the primary effect of insulin on blood glucose levels?
Lowers glucose levels
What is the primary effect of glucagon on blood glucose levels?
Raises glucose levels
Insulin and glucagon have _______ effects on blood glucose levels.
Opposite
Which hormone is responsible for increasing blood glucose levels?
Glucagon
Which hormone is responsible for decreasing blood glucose levels?
Insulin
What is positive feedback?
A self-reinforcing process that amplifies responses
Positive feedback loops are mechanisms that enhance or amplify changes; this can lead to exponential growth or decline.
What gas do ripening fruits emit?
Ethylene gas
Ethylene is a plant hormone that regulates the ripening process in fruits.
What effect does ethylene gas have on nearby fruits?
Stimulates accelerated ripening
This phenomenon is an example of a positive feedback loop in plant biology.
True or False: Positive feedback mechanisms always lead to stability in biological systems.
False
Positive feedback can lead to instability and rapid changes in biological systems.
What is cell division in prokaryotes called?
Binary fission
What happens during binary fission in prokaryotic cells?
The prokaryotic cell elongates as the DNA replicates. A new cell membrane and cell wall are synthesized producing two daughter
This process is a form of asexual reproduction in prokaryotes.
True or False: Binary fission results in the creation of one daughter cell.
False
Binary fission produces two daughter cells.
What are the five steps of Binary fission?
What are the steps of mitosis?
What is the cell cycle simply?
Series of events an organisms cells grow and divide to form two genetically identical diploid daughter cells
What are the main phases of mitosis?
Interphase and M phase (mitosis) and cytokinesis
What are Quiescent cells?
Cells that are not divided but can enter the cell cycle when stimulated - these cells are also known as the G_0 phase (when cells aren’t in the cell cycle)
What is the G_0 phase in the cell cycle?
Non-dividing cells that can enter and leave the cell cycle based on environmental signals and cues.
Do all cells divide at the same rate?
No, not all cells divide at the same rate.
What determines how often cells divide?
How often they are ‘used’ or exposed to damaging conditions.
What is the total time of the cell cycle if it is 24 hours?
Interphase: 23/24 hrs and Mitosis (M Phase): 1/24 hrs.
Fill in the blank: Some cells don’t go through the _______.
cell cycle.
What do developing organisms require for growth?
Production of new cells that each possess a complete genome
This is essential for the organism to grow and develop properly.
What occurs when cell production is greater than cell death?
Organismal Growth
This is a key factor in how organisms increase in size and complexity.
Why do cells go through the cell cycle in asexually reproducing organisms?
To pass their DNA to the next generation
This process ensures genetic material is transmitted during reproduction.
How do adult, multicellular organisms utilize the cell cycle?
To replace damaged or dying somatic (body) cells
This process is crucial for tissue repair and maintaining healthy body function.
What are the three main stages of the cell cycle?
Interphase, Mitosis (M Phase), Cytokinesis
What are the sub-stages of Interphase?
Growth 1, Synthesis of DNA (S phase), Growth 2
What is the first stage of Mitosis?
Prophase
What stage of Mitosis follows Prophase?
Prometaphase, then Metaphase
What is the third stage of Mitosis?
Anaphase
What is the final stage of Mitosis?
Telophase
What follows Mitosis in the cell cycle?
Cytokinesis
Fill in the blank: The S phase is responsible for _______.
Synthesis of DNA
True or False: Cytokinesis is a part of Mitosis.
False
What is the order of events in the interphase?
Growth 1, synthesis of DNA (S phase), growth 2
What are the three stages of the cell cycle?
Interphase, Mitosis (M Phase), & Cytokinesis
What is the purpose of Growth 1 (G1) in the cell cycle?
Grow and produce more important molecules and structures
What occurs during the DNA Synthesis (S) phase?
DNA REPLICATION ONLY
What happens during Growth 2 (G2) of the cell cycle?
Finish growing and produce more VIP molecules like nucleotides and enzymes and structures (organelles) in preparation for division
Fill in the blank: The first step of the cell cycle is _______.
Growth 1 (G1)
True or False: Cytokinesis is a part of Interphase.
False
What is the first step of mitosis?
Prophase
In prophase, the nucleus dissolves, DNA condenses, and chromosomes become visible. Spindle fibers also begin to form.
During which phase of mitosis do chromosomes line up on the equatorial plate?
Metaphase
In metaphase, spindle fibers attach to chromosomes, aligning them at the center of the cell.
What occurs during telophase?
Nucleus reforms and DNA decondenses
The cell membrane also starts to pinch in during telophase.
What is the primary action that occurs in anaphase?
Contract spindle fibers to move chromosomes to opposite poles
This ensures that each daughter cell will receive an identical set of chromosomes.
What is the final step of mitosis called?
Telophase
Fill in the blank: In prophase, the _______ dissolves.
nucleus
True or False: In metaphase, chromosomes are not visible.
False
Chromosomes are visible and aligned on the equatorial plate during metaphase.
What happens to the cell membrane during cytokinesis?
It pinches in to form two daughter cells
This process results in the division of the cytoplasm.
What is the first step of mitosis?
Prophase
In prophase, the nucleus dissolves, DNA condenses, and chromosomes become visible. Spindle fibers also begin to form.
During which phase of mitosis do chromosomes line up on the equatorial plate?
Metaphase
In metaphase, spindle fibers attach to chromosomes, aligning them at the center of the cell.
What occurs during telophase?
Nucleus reforms and DNA decondenses
The cell membrane also starts to pinch in during telophase.
What is the primary action that occurs in anaphase?
Contract spindle fibers to move chromosomes to opposite poles
This ensures that each daughter cell will receive an identical set of chromosomes.
What is the final step of mitosis called?
Cytokinesis
During cytokinesis, the cytoplasm divides, and the cell membrane pinches in to form two genetically identical daughter cells.
Fill in the blank: In prophase, the _______ dissolves.
nucleus
True or False: In metaphase, chromosomes are not visible.
False
Chromosomes are visible and aligned on the equatorial plate during metaphase.
What happens to the cell membrane during cytokinesis?
It pinches in to form two daughter cells
This process results in the division of the cytoplasm.
Here is the mitosis checklist
Here is the mitosis checklist
The levels of what type of molecule increase and decrease during the cell cycle?
Proteins known as cyclins
What do cyclins form complexes with?
Cyclin-dependent kinases (CDKs)
Cyclins are essential regulatory proteins that control the cell cycle by interacting with CDKs.
What is the primary role of cyclin-dependent kinases (CDKs)?
To phosphorylate target proteins that promote cell division
CDKs are activated by cyclins and play a crucial role in regulating the cell cycle.
How do cyclins affect CDKs?
They activate CDKs
The activation of CDKs by cyclins is essential for the progression of the cell cycle.
Fill in the blank: Cyclins and CDKs control the _______.
cell cycle
The interaction between cyclins and CDKs is vital for the orderly progression of the cell cycle.
True or False: Cyclins phosphorylate target proteins independently.
False
Cyclins must first activate CDKs, which then carry out the phosphorylation of target proteins.
Here is the interaction between cyclins and cyclin dependent kinases in the cell cycle
Here is the interaction between cyclins and cyclin dependent kinases in the cell cycle
What do cyclin-CK complexes control?
The cell cycle
Cyclin-CK complexes are critical for regulating the timing and progression of the cell cycle.
What activates cyclin-CK complexes?
Signals that promote cell division
These signals trigger the activation of cyclin-CDK complexes, allowing the cell cycle to progress.
Which phases of the cell cycle are controlled by different cyclin-CDK complexes?
G1/S phase, S phase, and M phase
Each cyclin-CDK complex is specific to a particular phase in the cell cycle, ensuring proper progression.
True or False: Cyclin-CK complexes are only involved in the M phase of the cell cycle.
False
Cyclin-CK complexes are involved in multiple phases, including G1/S and S phases.
What is required for cell cycle progression?
Successful passage through multiple checkpoints.
What does the checkpoint in G1 monitor?
Damaged DNA.
What does the checkpoint in G2 ensure?
That DNA has been fully copied. (This checkpoint is known as the DNA replication checkpoint)
What does the spindle assembly checkpoint in the M phase ensure?
That the spindles are attached to the chromosomes.
Fill in the blank: The DNA damage checkpoint is located in _______.
G1 phase.
Fill in the blank: The DNA replication checkpoint is located in _______.
G2 phase.
Fill in the blank: The spindle assembly checkpoint is located in _______.
M phase.
Image of checkpoints in cell cycle
How many checkpoints do cells pass through in the cell cycle?
3
What do cells check for at each checkpoint in the cell cycle?
Damage, mutations, and proper internal conditions
What happens to healthy cells in the cell cycle?
They complete the cell cycle
What occurs to damaged or mutated cells during the cell cycle?
They enter cell cycle arrest where the cell produces inhibitors of cyclin proteins to prevent progression through the cell cycle
What does a cell produce to prevent progression through the cell cycle?
Inhibitors of cyclin proteins
What is necrosis and when does it occur?
Process of cellular death when cells are exposed to extreme conditions
What is apoptosis and when does it occur
Pre planned cell death in the body as normal cellular multiplication to maintain cellular multiplication
What happens when there is a repairable damage or mutation in DNA of a cell?
It’s repaired and continues through the cell cycle eventually producing 2 identical daughter cells
What happens when there is an irreparable damage or mutation in DNA of a cell?
The goes through programmed cell death (apoptosis) and is eliminated and not daughter cells are produced. This prevents diseases
What happens when there is an irreparable damage or mutation in DNA of a cell?
The goes through programmed cell death (apoptosis) and is eliminated and not daughter cells are produced. This prevents diseases
What is the consequence of damage to DNA?
It can result in the addition of phosphate groups to p53 proteins from a kinase bringing the cell cycle to a halt in G phase because the P53 with a phosphate enters the DNA Turning a Gene on which pauses the cell cycle to give time for the cell to repair
G phase refers to the gap phase in the cell cycle where the cell prepares for DNA synthesis.
What do activated p53 proteins do?
They turn on genes that pause the cell cycle.
This action is crucial for preventing the proliferation of damaged cells.
Image of p53 in cell cycle
What type of protein is a p53?
Tumor suppressor protein
What can disruption of cell cycle checkpoints lead to?
Cell death or cancer
What type of mutations are common in some cancers?
Mutations in p53, rendering it nonfunctional
What is a key characteristic of cancer development?
Multiple mutations that promote cell division and remove normal checks on cell division
What does inactivation of p53 allow a cell to do?
Divide in the presence of DNA damage
What might a second mutation in a cancer cell do?
Accelerate cell division
What role does a third mutation play in cancer progression?
Interfere with cell cycle checkpoint
What is the effect of a fourth mutation in cancer cells?
Allow cells to migrate through the body
Fill in the blank: Cancer results from multiple mutations that promote _______ and remove the normal checks on cell division.
[cell division]
Just know this slide
P53 can trigger ___ or ___
Cell cycle arrest or apoptosis
What’s the difference of prophase and prometaphase
