Chapter 2 Bio Test Flashcards
Cite the cell theory
All living things are made up of one or more cells and their products.
The cell is the simplest unit that can carry out all life processes
All cells come from other cells; they do not come from non-living matter
What are prokaryotes?
→ Simplest organisms, single-celled life are archaea and bacteria which are called PROKARYOTES
Prokaryotes: a cell that does not contain a nucleus or other membrane-bound organelles
What are Eukaryotes?
→ More complex cells can exist as single-celled organisms or multicellular organisms which are called EUKARYOTES
Eukaryotes: a cell that contains a nucleus and other organelles, each surrounded by a thin membrane
→ include all protists, fungi, animals and plants and the tiniest amoeba to the largest whale
→ This cell has specialized parts called organelles that carry out specific functions necessary for life
What is the difference between eukaryotic and prokaryotic?
→ the cell of eukaryotic cells are much larger than the cells of prokaryotic
→ structure only in plant cells and not animal is cell wall, chloroplasts and a large vacuole
What are the similarities in animal and plant?
→ The cell membrane, cytoplasm, nucleus, mitochondria, endoplasmic reticulum, golgi body and vacuoles are in both plant and animal cells
What basic activities do cells have to perform?
→ all cells have to perform the same basic activities to stay alive: use energy, store materials, take materials from the environment, get rid of wastes, move substances to where they are needed and reproduce
→ Each organelle has a specific function within the cell
Name the organelles in a plant cell
Chloroplast
Cell well
Cell membrane
Vacuole
Cytoplasm
Ribosome
Endoplasmic reticulum
Nucleus
Nuclear membrane
Mitochondrion
Golgi body
Name the organells in a animal cell
Cytoplasm
Golgi body
Cell membrane
Mitochondria
Vacuole
Nucleus
Nuclear membrane
Ribosome
Endoplasmic reticulum
What is the cytoplasm?
→ All the organelles inside the cell are suspended in the cytoplasm
→ cytoplasm is mostly water but contains other substance that the cell stores until they are needed
→ Many chemical reactions take place within the cytoplasm which can change from helly like to liquid which allows organelles to be moved around
What is the cell membrane?
→ surrounded by a flexible double layered cell membrane
→ function is both to support the cell and to allow some substances to enter while keeping others out (ex. Water and oxygen molecules can but larger molecules like protein can’t)
→ Because of this, cell membrane is called a semi permeable membrane
What is the nucleus?
→ roughly spherical structure within the cell
→ contains genetic information that controls all cell activities
→ this genetic information is stored in chromosomes
→ Chromosome contain DNA (deoxyribonucleic acid, material in the nucleus of a cell that contains all cells genetic info) like coded instructions for all cell activity
→ When a cell divides, the DNA is copied so that each new cell has a complete set of chromosomes
What is the mitochondria?
→ power plants because the make energy available to the cell
→ Active cells, muscle cells, have more mitochondria than less active cells, such as fat-storage cells (they have one or two mitochondria)
→ Cells store energy as a form of glucose
→ Mitochondria contain enzymes that help to convert the stored energy into an easily usable form ← cellular respiration which requires oxygen and waste products are carbon dioxide and water
Glucose + oxygen → carbon dioxide + water + usable energy
What is the endoplasmic reticulum?
→ 3D network of branching tubes and pockets that extends throughout the cytoplasm and is continuous from the nuclear membrane to the cell membrane
→ These fluid-filled tubes transport materials, such as proteins, through the cell
→ In the brain, it assist with production and release of hormones
→ In muscles, it is involved with muscle contraction
What are the golgi bodies?
→ Collect and process materials to be removed from the cell
→ Make and secrete mucus
→ Cells that secrete lost of mucus like in the lining of the intestine have many golgi bodies
What are vacuoles?
→ single layer of membrane enclosing fluid in a sac
→ functions vary according to type of cell
→ some functions are containing some substances, removing unwanted substances from the cell and maintaining internal fluid pressure (turgor)
→ Animal cells: have small vacuoles that are not visible
→ Mature plant cells: have one central vacuole
What are ribosome?
→ site of protein synthesis
→ Ribosomes are the “protein factories” of the cell, responsible for translating the genetic code from mRNA into proteins.
What is nuclear membrane?
a double-layered structure that surrounds the nucleus of eukaryotic cells, separating the genetic material (DNA) from the cytoplasm and regulating the movement of molecules in and out of the nucleus
→ controls what enters and exits the nucleus
What is the cell wall?
→ outside of cellular membrane
→rigid but porous structure made of cellulose
→ provides support for the cell and protection from physical injury
→ cell wall may hold together long after plant dies
–> Animal cells don’t have cell walls primarily because animals need flexibility and mobility, and a rigid cell wall would hinder these functions.
What is the vacuole in plants?
→ Have one large vacuole, which take up most of the space in the cell
→ When they are full of water, turgor pressure keeps the cells plump which keeps the plant’s stems and leaves firm
→ If water level is low, the vacuole lose turgor pressure and the cells become soft and the plant stems and leaves become limp and droopy until water is added
What are chloroplasts?
→ The cells of leaves have a structure called chloroplasts
→ they contain chlorophyll and give leaves their green color
→ Chloroplasts absorb light and energy which is used in photosynthesis (the process of converting carbon dioxide and water in glucose and oxygen)
Carbon dioxide + water + energy (sunlight) → glucose + oxygen
→ photosynthesis allows plants to obtain their energy from the sun so they can make their own food
Do plants rely on mitochondria?
→ Plants rely on mitochondria to metabolize glucose like animal cells do
–> Plants rely on mitochondria because these organelles are crucial for generating the energy (ATP) needed for various cellular processes, including respiration and metabolism, especially during periods when photosynthesis is not occurring, like at night or in non-photosynthetic tissues.
What is metabolism?
metabolism is your body’s process of converting food and drink into energy, enabling vital functions like breathing, moving, and thinking
What is the stage?
Stage: supports the microscope slide, has a central opening that allows light to pass through the slide
What are the clips?
Clips: hold the slide in position on the stage
What is the diaphragm?
Diaphragm: controls the amount of light that reaches the object being viewed
What are the objective lenses?
Objective lenses: magnify the object, have 3 possible magnifications: low power (4x), medium power (10x), and high power (40x)
What is the body tube?
Body tube: contains the eyepiece (ocular lens), supports the objective lenses
What is the eyepiece? What is it also called?
Eyepiece(ocular lens): the part you look through to see, magnifies the image of the object, usually be 10x
What is the revolving nosepiece?
Revolving nosepiece: holds the objective lenses, rotates, allowing the objective lenses to be changed
What is the find-adjustment knob?
Find-adjustment knob: moves the tube to get the object into sharp focus, used with medium power and high power magnification, used only after the object has been located, centred and focused under low power magnification
What is the coarse adjustment knob?
Coarse adjustment knob: moves the body tube up or down to get the object into focus, used with low-power objective lens only
What is the light source?
Light source: may be an electric light bulb or a mirror that can be angled to direct light through the object being viewed
What is the magnification formula and for each piece?
→ total magnification = (ocular lens power) x (objective lens power)
→ eyepiece = 10x
→ low power objective = 4x
→ medium power objective = 10x
→ high power objective = 40x
Why do cells divide?
For reproduction, growth and repair
What is asexual reproduction?
Asexual Reproduction: the process of producing offspring from only one parent; the production of offspring that genetically identical to the parent (mitosis)
What is sexual reproduction?
Sexual Reproduction: the process of producing offspring by the fusion of two gametes; the production of offspring that have genetic information from each parent (miosis)
What happens as organisms grow?
→ all organisms grow
→ as multicellular organisms grow, their genetic information duplicates and the number of cells increases
→ both plants and animal cells need the same thing: energy, nutrients, water and gases
→ the movement of chemicals used during cell activity and growth is called diffusion
What is diffusion?
Diffusion: the movement of molecules (or other particles) from an area of high concentration to an area of low concentration until they are evenly distributed
What is concentration?
Concentration: the number of molecules of a substance (solute) in a given volume
What is osmosis?
Osmosis: involves the diffusion of water molecule across a membrane in response to centration differences
→ for osmosis, water always moves toward where the solution is more concentrated
–> specific type of diffusion where water molecules go from a high concentration of water to a low concentration fo water THROUGH A MEMEBRANE
Why do cells use diffusion?
→ Cells transport important nutrients and oxygen through the cell membrane using diffusion
What is an isotonic solution and the effect on red blood cells?
→ Red blood cells work best in an isotonic (slightly salty and equal water in + out with net 0 movement) solution
–> water in = water out
→ If our blood shifts in salt levels, our red blood cells can expand or shrink
What solution do plant cells work best in and why?
→ Plants cells work best in a hypotonic (more water, less solute) solution
–> In a hypotonic solution, water moves into plant cells, causing them to become turgid and maintain their rigidity, something that’s absolutely essential for the health and growth of the plant.
→ This allows the central vacuole to fill with water
Explain the different solution that can occur in an animal cell
→ In an isotonic solution, there is no net movement of water (best)
→ In a hypotonic solution, water enters the cell which may burst (lysis) where there is more water outside
→ In a hypertonic solution, water leaves the cell, which shrivels (crenation) = dehydration where there is less water outside
Explain the different solution in plant cells
→ In an isotonic solution, there is no net movement of water
→ In a hypotonic solution, the central vacuole fills with water, turgor pressure develops and chloroplasts are seen next to the cell wall (best)
→ In a hypertonic solution, the central vacuole loses water, the cytoplasm shrinks (plasmolysis) and chloroplast are seen in the center of the cell
Explain the reparation of cells
→ Your body replaces dead skin cells every day
→ Your body replaces each red blood cell about every 120 days
→ Every cut and blister need new cells to fill in the gaps
→ All organisms need to repair themselves to stay alive
How does surface area affect the efficency of the cell?
A larger surface area to volume ratio is more efficient than a smaller ratio. This is due to the amount of plasma membrane relative to the volume of the cell. The more plasma membrane available to transport materials in and out of the cell, the more efficient the cell will be in completing its specific functions.
Every cell has a limit of surface area to volume ratio to ensure that the exchange of resources and waste occurs quickly enough for the cell to survive. If cells were too big, diffusion would take an extremely long time, and a cell could die from starvation or poison itself with its wastes.
A cell’s efficiency in exchanging materials with its environment is directly related to its surface area-to-volume ratio (SA:V) – a higher SA:V ratio means more surface area relative to volume, leading to more efficient material exchange.
Surface Area and Volume:
As a cell grows larger, its volume increases faster than its surface area. This means that a larger cell has less surface area relative to its volume, making it harder to efficiently transport materials in and out.
Efficiency of Exchange:
A higher SA:V ratio allows for more efficient absorption of nutrients and removal of waste products. This is because there’s more membrane area for materials to cross.
Cell Size and Shape:
Cells are often small and have specialized shapes (like folds or villi) to maximize their surface area and maintain a high SA:V ratio. For example, intestinal cells have villi to increase the surface area for nutrient absorption.
Examples:
Mitochondria: The inner membrane of mitochondria (where energy production occurs) has folds (cristae) to increase surface area, allowing for more efficient energy production.
Intestinal Cells: The folds and villi in the lining of the small intestine increase the surface area for efficient absorption of nutrients.
Red Blood Cells: Red blood cells are biconcave disks, which increases their surface area relative to their volume, facilitating efficient gas exchange.
Diffusion:
A high SA:V ratio also facilitates faster diffusion of substances across the cell membrane.
Metabolic Rate:
Smaller organisms with a higher SA:V ratio have a higher metabolic rate to maintain body temperature because they lose heat faster.
What cell size is best?
For efficient material exchange, it’s generally better for a cell to have a higher surface area to volume ratio (SA:V) because a larger surface area relative to volume facilitates faster diffusion of nutrients and waste products
When cells become too large, their SA:V ratio decreases, making diffusion less efficient, which can lead to cell division to restore a more favorable SA:V ratio
Root hairs in plants and the folds in the small intestine are examples of adaptations that increase surface area to enhance nutrient absorption.
How are eukaryotic cells still efficent even though they are large?
Eukaryotic cells, despite their larger size, remain efficient due to compartmentalization and specialized structures called organelles that enable efficient transport and function.
Organelles facilitate the efficient transport of materials within the cell, preventing the reliance on slow diffusion processes.
The presence of organelles enables eukaryotic cells to carry out complex processes that would be difficult or impossible for simpler, prokaryotic cells.
While larger cells have a lower surface area to volume ratio, organelles help overcome this limitation by enabling efficient internal transport and specialized cellular activities.
Division of Labor:
The compartmentalization of eukaryotic cells allows for a “division of labor,” where different organelles perform specific tasks, enhancing overall cellular efficiency.
The membranes in the organelles increase teh surface area avaibale for chemical reactions to take place.
Eukaryotic cells can grow larger than prokaryotic cells due to specialized organelles that enhance cellular transport and compartmentalization. Their complex structure allows for efficient nutrient uptake and waste expulsion, despite having a lower surface area-to-volume ratio
Why do we need a lot of cells?
- They are specialized to compplete various tasks
- Cells are dying all the time so extra cells have to be replaced
- small cells transport materials in and out quickly than large ones for the same processes
What is surface area of a cell and what is it useful for?
Defined as the amount of surface covering the outer part of the cell. Comparing the surafec area to volume ratio, the efficieny of the cell at transporting materilas in and out is found out.
LARGER THE RATIO, THE MORE EFFICIENT THE CELL IS>
What increases the surface area inside the cell?
The addition or organelles
What is cancer?
Cancer: a group of diseases in which cells grow and divide out of control
How does cancer form and what does it prevent?
→ It results from a change in the DNA that controls the cell cycle.
→ This change prevents the cells from staying in interphase for the normal amount of time.
→ One or more of the checkpoints fails, so the cell and all of its subsequent daughter cells continue to divide uncontrollably.
How can cancer be obtained?
→ Some types of cancer run in families, whereas others are triggered by environmental factors.
→ Some cancers may have both hereditary and environmental causes.
→ Cancer is not infectious: you cannot catch it from someone who has it.
→ Cancer is a serious concern for humans, but many other organisms, such as cats, dogs, fish, and even plants, can also develop cancer.
What does a cancer cell do?
→ A cancer cell is one that continues to divide despite messages from the nucleus or the surrounding cells to stop growing and dividing. The cell’s checkpoints may fail to identify problems or kill off the cell.
What is a tumour?
Tumour: The uncontrolled growth and division may create a rapidly growing mass of cells that form a lump or tumour
What is a benign tumour?
Benign tumour: The cells of the tumour may stay together and have no serious effect on surrounding tissues.
→ Cells in a benign tumour are not cancerous.
→ However, sometimes a benign tumour can grow so large that it physically crowds
nearby cells and tissues. This can affect their normal function.
What is a malignant tumour?
Malignant tumour: A mass of cells is a malignant tumour if it interferes with the function of neighbouring cells and tissues, such as the production of enzymes or hormones.
→ Malignant tumours may even destroy surrounding tissues.
→ The cells in a malignant tumour are considered cancerous.
What is metastasis?
In some cases, cancer cells break away from the original (primary) tumour and move to a different part of the body.
If they settle there and continue growing and dividing uncontrollably, they can start a new (secondary) tumour.
This process is known as metastasis and is one of the reasons why cancer is such a dangerous disease.
How does cell division usually work without erros?
→ Every time a cell divides, its DNA is faithfully duplicated.
→ Usually, this process is error-free and the genetic information in the daughter cells is exactly the same as that in the parent cell.
What are mutations?
Mutations: Sometimes, however, random changes occur in DNA. These random changes are known as mutations.
How do mutations affect the DNA and cell division?
→ These changes may either result in the death of the cell or allow the cell to survive and continue to grow and divide.
→ Very rarely, the change occurs in the DNA that controls cell division. Once this crucial cell cycle DNA starts behaving abnormally, the cells may become cancerous and proliferate wildly through repeated, uncontrolled mitosis and cytokinesis.
→ They multiply until all nutrients are exhausted.
What causes mutations?
→ Some mutations are caused by carcinogens: environmental factors that cause
cancer.
→ Well-known carcinogens include tobacco smoke; radiation, such as X-rays and UV rays from tanning beds and sunlight; some viruses, such as human papillomavirus (HPV) and hepatitis B; certain chemicals in plastics; and many organic solvents.
What is a major challenge for cancer researchers with carcinogens?
→ If a group of people is exposed to a carcinogen, some will develop cancer, but others will not. → This is a major challenge for cancer researchers because they cannot predict who will develop cancer.
Why do most people get cancer?
→ Some cancers appear to be at least partly hereditary. This means that the DNA passed from one generation to the next may contain information that leads to disease.
→ These cancers include some breast cancers and some colon cancers. A genetic link makes it more likely that you will develop a particular type of cancer, but it does not guarantee that you will get cancer
What is the most common types of cancer in Canada? Why?
→ Lung cancer is one of the most common types of cancer in Canadians over 40.
→ Carcinogens in tobacco affect more than just the lungs. Smoking also increases the risk of over a dozen other types of cancer
→ The good news is that most of these smoking-related cancers can be prevented by giving up smoking—or never starting in the first place and staying away from second-hand smoke
What is cancer screening?
→ Cancer screening means checking for cancer even if there are no symptoms. Different types of cancer can be screened for in different ways.
→ Cancer screening can be done at home, as part of a routine medical checkup, or
with a special appointment.
Why is screening important?
→ Screening is especially important for people who have a family history of certain cancers (such as breast cancer or colon cancer). If you have a family history of cancer, you may choose to go through genetic screening. This will determine if you have inherited DNA that is linked to cancer.
→ Screening can also be valuable for people who are exposed to carcinogens at work or because of their lifestyle.
→ Screening does not prevent cancer, but it does increase the chance of detecting cancer early enough to successfully treat it. This is one important way to reduce your risk.
Why should young women and men become screened?
→ Many women take responsibility for their health by performing regular breast self-examinations to check for lumps that may indicate breast cancer. Women can also be screened for early signs of cervical cancer, starting around age 18, by getting a regular Pap test. This is a procedure in which a doctor takes a sample of cervical cells, which are checked for cancer. Men can detect testicular cancer early through testicular self-examination.
What is a pap test?
Pap test: a test that involves taking a sample of cervical cells to determine if they are growing abnormally
What is the PSA test (blood test)?
→ There is also a blood test, called the PSA test, that a doctor can prescribe to screen for prostate cancer. This is not widely used for men under the age of 50 as the incidence of prostate cancer is lower for that age group.
What do other screening test with blood test test for?
→ Other screening tests include a blood test for colon cancer and regular skin checks by a doctor or dermatologist to look for changes in moles, new growths, and sores. You can learn to check your own skin regularly for moles.
What are the risks of getting cancer?
→ These risks include your personal and family medical history, carcinogens in your environment, and your lifestyle choices.
What lifetstyle changes should be made to reduce risk of developing cancer?
→ There are many lifestyle choices, besides avoiding tobacco smoke, that can help reduce your risk of developing cancer.
→ A healthy diet including a lot of fruits and vegetables and less fatty meat may help. Research has shown that certain “super foods” contain substances that help your body protect itself
from cancers
→ Even though vitamin supplements may include some of these substances, the best way to obtain them is by eating the food itself. These super foods do not prevent cancer; rather, they lower your cancer risk.
→ The risk of some cancers increases with the amount of body fat a person has. A healthy diet may aid weight loss, which could lower the risk of cancer.
Why is it important for a cancer to be diagnosed early?
→ A growing tumour creates swelling or causes discomfort. In other cases, the patient may feel very tired or start losing weight for no apparent reason.
→ The earlier a cancer is diagnosed, the better the chances of it being successfully treated. If cancer is suspected, the doctor will order medical tests to investigate further. These tests can include blood tests and special imaging technique
What are the different types of imaging techniques?
→ Imaging techniques may include endoscopy, X-ray, ultrasound, CT scanning, and MR
What is an endoscope?
→ An endoscope is commonly used to screen for colon cancer.
→ The endoscope is made up of a fibre-optic cable to deliver light, a tiny camera, and a cable that sends the images to a screen .
→ Tools, such as forceps, can also be attached. The patient may be given a sedative before the endoscope is inserted into the colon through the rectum.
→ The camera allows the doctor to look for abnormal growths. Forceps can be used to remove
a small sample (biopsy) of any suspicious-looking growth. The sample can then be studied under a microscope
What is an X-ray?
→ Doctors use X-ray images to view parts of the body such as bones and lungs
What are the downsides of X-rays?
→ X-rays can also cause DNA damage.
→ They are particularly harmful to rapidly dividing cells such as those in a growing fetus. For this reason, women who are pregnant should not undergo X-ray examination
What is a mammogram?
→ A specialized X-ray technique for imaging breast tissue
What is a ultrasound?
→ Ultrasound imaging uses ultra–high-frequency sound waves to create a digital image.
→ The digital image allows doctors to view certain soft tissues, such as the heart or the liver
What is a CT scan?
→ (computerized axial tomography)
→ A CT scan allows the X-ray technician to take multiple X-rays of the body from many different angles.
→ The images are then assembled by computer to form a series of detailed images.
→ This technology allows doctors to view parts of the body that cannot be seen with a conventional X-ray scan
What is a MRI?
→ A fourth imaging technique is MRI (magnetic resonance imaging)
→ In an MRI, radio waves and a strong magnetic field create images with more detail than a CT scan.
→ Computers can assemble the information into three-dimensional model
Why are these imaging techniques important?
→ If any of the medical tests or images show abnormalities, the next step is to examine a sample of the suspected cancer cells under a microscope. This is the only way to confirm a diagnosis of cancer.
What is leukemia?
→ Leukemia is a cancer that affects the blood, often resulting in a high ratio of white blood cells to red blood cells.
Which cell samples can be obtained easily?
→ Certain cell samples can be obtained easily, such as blood cell samples.
What does taking a biopsy mean?
→ A sample of tumour cells may have to be removed surgically. This technique is known as “taking a biopsy.” The sample is then viewed under a microscope. It may also be tested for genetic abnormalities.
What do cancer cells look like?
→ Cancer cells are often irregularly shaped and may be smaller or larger than the surrounding cells.
What do doctors do after diagnosis?
→ After diagnosis, the doctors must discover where the cancer originally began.
→ They also need to find out how large the tumour is, how quickly it is growing, and whether the cancer has spread.
→ This information helps to determine suitable treatments and to predict the outcome
What is the goal of cancer treatment?
→ The goal of cancer treatment is to slow down the growth of the tumours or destroy as many cancer cells as possible.
What are the methods of treating cancer?
→ Currently, there are three main conventional methods of treating cancer: surgery, chemotherapy, and radiation therapy.
→ An emerging technique is biophotonics.
→ A cancer treatment plan may consist of one or a combination of these methods.
What is the surgery method?
→ Physically removing the cancerous tissue is sometimes the preferred way of treating cancer.
→ If the tumour is easily accessible and fairly well defined, the doctors may recommend this option
What is chemotherapy?
→ Chemotherapy is a method of treating cancer using drugs.
→ These work by slowing or stopping the cancer cells from dividing and spreading to other
parts of the body, and by killing the cells.
→ The drugs can be injected or taken orally (by mouth). Side effects may include hair loss, nausea, and fatigue, but the benefits of the treatment generally outweigh the negative effects.
→ Chemotherapy is often one of the first stages of cancer treatment.
What is the aim for chemotherapy?
→ Its aim is to shrink a tumour for surgical removal or for radiation treatments.
What is an advantage of chemo?
→ A huge advantage of chemotherapy is that the drugs travel throughout the body and reach almost all tumours, even if they are much too small to be detect
What is the radiation method?
→ Cancer cells are easily damaged by ionizing radiation because they divide rapidly. Radiation therapy takes advantage of this.
→ The DNA of many of the daughter cells is damaged by the radiation, so the cells cannot divide further.
→ The radiation is directed at the tumour either by using a focused beam or by implanting a radioactive source into the tumour. This minimizes side effects
What happens when the cell gets too big?
→ When cells get too big, they undergo cell division
→ This cell division doubles the number of cells every time it goes through a cell cycle
→ The cell cycle always continues
→ This is asexual reproduction
–> When a cell grows too large, it can’t efficiently transport materials in and out, and it may eventually die. This is because the cell’s surface area-to-volume ratio decreases as it gets larger, making it harder for nutrients and waste to diffuse across the membrane. To avoid this, cells typically divide into smaller cells before they become too large
Explain why different cells divide rapidly versus never
→ Some cells divide rapidly (embryonic cells)
→ Other body cells may require 30 h to divide
→ Adult nerve cells may never undergo cell division
In conclusion, some cells divide faster than others because they are specialized to perform specific functions. Cancer cells fall into the category of cells that divide rapidly.
As cells continue to specialize in a certain set of functions, they lose the capacity to divide. Neurons are extremely specialized cells. Due to their unique power and function within the body, the connections and pathways that are established between nervous centers are interconnected and valuable.
What does mitosis not make?
→ Mitosis DOES NOT make sperm or egg cells (meiosis)
What happens in interphase? Why is it important?
→ The cell spends its majority of its time here
→ Longest stage but it is not the resting stage
→ The cell is carrying out all life activities, expect division
→ During this stage, the genetic material, DNA (deoxyribonucleic acid), is in very long, thin, invisible strands called chromatin
→ When the cell prepares for cell division, the strands are duplicated so that there are two identical strands of genetic material
→ This duplication is critical before mitosis
→ The cell grows, replicates DNA (only for mitosis) and continues its cell function here
→ Interphase happens before mitosis
→ cellular respiration occurs here
Why cell division importnat?
→ no cell division, no growth
–> Cell division is crucial for growth, repair, and reproduction, as it allows organisms to replace old or damaged cells, develop from a single cell into a complex organism, and, for some organisms, reproduce.
What are the two stages for cell division?
Mitosis and cytokinesis
Give a summary of mitosis
→ Make body cells
→ the division of the contents of the nucleus
→ Has four phases: prophase, metaphase, anaphase and telophase
Give a summary of cytokinesis
→ the division of the rest of the cell, such as cytoplasm, organelles, and cell membrane
→ each cell division produces two genetically identical cells called daughter cells
→ CELLS DO NOT DIVIDE ALL THE TIME
Why dont cells divide all the time?
Cells don’t divide all the time due to a combination of factors, including cellular communication, telomere shortening, and the need to maintain a healthy balance of cell growth and function. These factors ensure that cells divide only when necessary for growth, repair, or replacement, preventing uncontrolled growth that can lead to diseases like cancer.
What happens in early prophase?
→ Early prophase: the cell prepares for division by condensing chromatin into visible chromosomes, the nuclear envelope begins to break down, and the mitotic spindle starts to form
What happens in late prophase?
→ Late prophase: In late prophase (also known as prometaphase), the nuclear envelope breaks down, chromosomes condense further, and the mitotic spindle begins to capture and organize the chromosomes, with microtubules attaching to the centromeres
What happens to the chromatin and nucleus in prophase?
→ Chromatin condense to form chromosomes (made of DNA and protein)
→ Each duplicated chromosome appears as two identical sister chromatids joined at their centromeres (a protein)
→ Chromatin coils and become chromosomes to make them easier to move in the cell
→ Aster/spindle fibers beings to form and stretch across the cell
→ Nuclear membrane disappears
→ 2 opposite poles are in the cell
→ Chromatin coils and become chromosomes to make them easier to move in the cell
→ nuclear membrane is getting rid of
→ nucleus is still present but starts to fade
How many chromosomes are there?
→ there are 46 chromosomes and 23 chromatids/pairs
Give a summary of prophase
In prophase, the first stage of mitosis, chromosomes condense, becoming visible as distinct structures. The nuclear envelope breaks down, and the centrosomes move to opposite poles of the cell, initiating the formation of the mitotic spindle. The nucleolus also disappears, and the duplicated chromosomes, composed of two sister chromatids joined at the centromere, become visible, often appearing as “X” shapes.
What happens in metaphase?
→ double stranded chromosomes line up along the MIDDLE of the cell (the metaphase plate or equator)
→ Makes them organized
→ only metaphase lines them up
→ If chromosomes were not connected to spindle correctly, they will not be separated correctly
→ no nucleus
→ spindles connect to centromeres
What happens in anaphase?
→ This is the shortest phase
→ Centromeres are separated and split in half
→ Each chromosome splits into TWO sister chromatids
→ The two sister chromatids move to opposite ends of the cell
→ the cell starts stretching out
→ spindle retract
→ by the end, the two ends of the cell have equivalent (complete) sets of chromosomes
→ spindles are fibres that help move chromosomes to the ends, the chromosomes don’t move by themselves
→ Centrosomes forms the spindles
What happens in telophase?
→ End goal is two cells
→ Two daughter nuclei form and nuclear envelope reform
→ Chromosomes become less condensed
→ Mitosis is complete
→ In plant cells, a cell plate (baby cell wall) is produced and eventually forms a new cell between the daughter cells
→ opposite of prophase
→ the chromosomes stretch out again into chromatins
→ spindles aren’t needed anymore
→ animal cells starts to pinch off (cytoplasm pinching)
What is difference between animal and plant cells in telophase/cytokinesis?
The primary difference between animal and plant cells during telophase lies in cytokinesis, the division of the cytoplasm. In animal cells, a cleavage furrow forms, pinching the cell membrane inward to separate the two daughter cells. In contrast, plant cells form a cell plate between the two new nuclei, which grows outwards to create a new cell wall and separate the daughter cells.
What happens in cytokenisis?
→ After mitosis
→ Division of cytoplasm
→ Two daughter cells appear
→ In animal cells, a cleavage furrow formed, which pinches the cell in two
→ chromosomes turn to chromatin
→ final separation
What are the checkpoints in the cell cycle?
→ the cell’s activities are always controlled at checkpoints
→ specialized proteins monitor cell activities and send messages to the nucleus to determine whether the cell should divide
What do the checkpoints in the cell cycle look for? What do they do?
→ they also check if the chromosomes were copied before mitosis
→ if the DNA is damaged, there may be enough time for the cell to repair the damaged DNA
→ if there is too much damage to the DNA, the cell is usually destroyed. This is a vital process that helps keep organisms healthy
→ these proteins check if the cell is growing enough, does it have the resources it needs to continue, if DNA was replicated properly
Why don’t some cells divide or go through these phases?
→ Some cells don’t divide or go through these phases, they are not preparing to divide
→ They are still performing cell functions
→ Some cells stay here temporarily if there are not enough resources
→ Many types of neurons in brain and spine stay here permanently where they won’t divide
→ This is why injuries, here make it hard to heal as cells can’t replicate
What is the cell cycle?
The cell cycle is the ordered series of growth and division that a cell undergoes to produce two new daughter cells
What is turgor pressure?
turgor pressure is the internal water pressure within a plant cell that pushes the cell membrane against the cell wall, making the plant firm and rigid.
SImilarties between prokaryotic and eukaryotic
cytoplasm, which consists of the jelly-like cytosol inside the cell, plus the cellular structures suspended in it; genetic material in the form of DNA; and. ribosomes, which are structures that build the cell’s proteins.
difference between smooth ER and rough ER
As discussed below, there are two distinct types of ER that perform different functions within the cell. The rough ER, which is covered by ribosomes on its outer surface, functions in protein processing. The smooth ER is not associated with ribosomes and is involved in lipid, rather than protein, metabolism. making fats and oils for diffrenet functions
What are lysosomes?
teh cell’s garbage and recycling facility. It has chemcials to break down food, cell waste, and foreign particles that enter the cell such as bacteria and viruses. It dgests and destorys dead calls or old cell parts, as well as recylces material to make other cells
What does the DNA control?
Yes, DNA controls cell division. The instructions encoded in DNA determine which proteins are made in a cell, and these proteins, in turn, regulate cell growth, division, and other cellular functions. The cell cycle, the ordered series of events that leads to cell division, is tightly controlled by specific genes and proteins that ensure proper DNA replication, repair of errors, and equal distribution of chromosomes to daughter cells
