Cells Flashcards
Cell Theory
- All living things are made up of one or more cells
- The cell is the simplest unit of life
- All cells come from other cells-they do not come from non-living matte
2 types of cells
Eukaryotes: with a nucleus
And
Prokaryotes: without a nucleus
Organelles
• “little organs”
• Cells have specialized parts that carry out specific functions
• Cells have many types of organelles that all work together
-Some are found ONLY in animal and plant cells
Cytoplasm (in both plant and animal cells)
• Aqueous (water-based) solution inside the cell
• Organelles are suspended in here
Cell Membrane (in both plant and animal cells)
• A thin, double layered film that separates the interior of the cell from the external environment
• Supports the cell and controls movement in and out of the call(‘semi permeable)
Nucleus (in both plant and animal cells)
• “control centre”- directs all cell’s activities
• contains the cell’s DNA (genetic information) on chromosomes
Mitochondria (in both plant and animal cells)
• produce energy for the cell via cellular respiration
Formula: glucose + oxygen ~ carbon dioxide + water + usable energy (Cellular Respiration(opposite of photosynthesis))
• have an inner and outer membrane
• cells that require lots of energy (ex.muscle cells) will have more mitochondria
Endoplasmic Reticulum (in both plant and animal cells)
• system of tubes and canals around the nucleus
• transport materials (ex.proteins and lipids(fat)) through cells
Golgi Apparatus (in both plant and animal cells)
•several tubes- look like a stack of flattened balloons
• packages materials to be removed from cell
• secretes mucus
Vacuoles (in both plant and animal cells)
• membrane bound sacs filled with a watery solution
• Animal Cells: Have many small vacuoles
• Plant Cells: Have one large vacuole
Cell wall
• plant cell only
• tough, rigid layer that surround cell- made of cellulose
• provides support and structure
Chloroplasts
• only in plant cells
• contains all the chemicals (chlorophyll) for photosynthesis
Formula: carbon dioxide + water + energy(light) = glucose + oxygen (Cellular photosynthesis (opposite of respiration))
• plant cells will then use mitochondria to produce usable energy
Lysosomes
• only in animal cells
• contain proteins that can break down molecules (ex. food brought in from extracellular space or bacteria/viruses)
• they are like a garbage dump for a cell
Two types of reproduction(1)
Asexual Reproduction:
• involves only ONE parent
• the offspring are identical to the parent
Two types of reproduction(2)
Sexual Reproduction:
• involves TWO parents
• offspring have characteristics of both parents
• every human call has 46 chromosomes
• one special “Half Cell” from each parent combines to make a new cell
Half Cells
•contains 23 chromosomes
• called gametes
• 2 gametes combine to make 1 cell with a full set of chromosomes
• this is why offspring have characteristics of both parents
2 processes all cells must do
- Aquire Nutrients
- Remove Waste
-chemicals and water must pass the cell membrane to get in or out
-these are moved in and out of the call by Diffusion and Osmosis
-small + uncharged molecules
Diffusion
Chemicals move from an area of high concentration to an area of low concentration (no energy required)
Osmosis
Water moves in the direction which has a greater concentration of solutes ( less concentrated ~ more concentrated, solute hinders the passage of water molecules)
Why must cells divide?
Overtime, you can’t supply nutrients or remove wastes from all parts of the cell fast enough to meet its needs
Cell Cycle: Stage 1
Interphase(longest phase)
• Cells grow and prepare to divide
• Cells perform their normal function
•DNA is copied
Cell Cycle: Stage 2
Mitosis
• Cell division occurs
• DNA in nucleus is divided into
Cell Cycle: Stage 3
Cytokinesis
• Cytoplasm, organelles, and cell membrane divided to form 2 identical cells
• Final part of cell division
• Two identical daughter cells are produced
Mitosis
• 4 stages of the replication of the molecules
• PMAT
Prophase
• the first stage of Mitosis
• the chromosomes condense and become visible
• the centrioles form and move toward opposite ends of the cell (“the poles”)
• the nuclear membrane dissolves
• spindle fiber from each centriole attach to each sister chromatid
Metaphase
• second stage of Mitosis
• the centrioles complete their migration to the poles
• the chromosomes line up in the middle of the cell (“the equator”)
Anaphase
• third stage of Mitosis
• spindles attached to chromatids and begin to shorten
• this exerts a force on the sister chromatids that pull them apart
• spindle fivers continue to shorten, pulling chromatids to opposite poles
• this ensures that each daughter cell gets identical sets of chromosomes
Telophase
• fourth stage of Mitosis
• the chromosomes decondenses (stretch out)
• the nuclear membrane reform
• cytokinesis reaches completion, creating two daughter cells
• in animal cells the cell membrane pinched creating two new cells
• in plant cells a new cell wall is built between the two cells
What controls when a cell starts and stops dividing?
The nucleus instructs the cell whether to divide or not. To help make these decisions the nucleus collects messages from the cells surrounding in the form of chemical signals or “checkpoints”
The nuclear keeps the cell in interphase if:
• signals from surrounding cells tell the cell to not divide;
• signals from the surroundings let the cell know there are not enough nutrients to provide for the growth of new cells;
• the DNA within the nucleus itself has not yet been replicated;
• the DNA within the nucleus is damaged
What happens when a mutation does occur?
The cell does not divide
The 2 types of tumors: Benign tumor
• cell division is unchecked and proceeds at a moderate rate
• does not invade surrounding cells, but may physically crowd nearby cells and tissue
• does not spread to other parts of the body
• relatively harmless unless found in a part of the body, such as the brain, where it may press on (crowd out) other cells
• Benign tumors are referred to as non-cancerous
The 2 types of tumors: Malignant tumors
• cell division is unchecked and occurs very quickly. Cells spend little time in interphase
• damages and destroys surrounding tissue
• can undergo metastasis, in which cancer cells break away from the original (primary) tumor and move to a different part of the body and start a new (secondary) tumor
• may interfere with the function of the other cells, sometimes resulting in death if the tumor is not destroyed or removed
• a part of the tumor can be removed surgically and put through tests to determine if the tumor is benign or malignant this is called a biopsy
How do these cancers actually become fatal?
Cancer will eventually take over enough of the cells in the location to greatly affect what that body part is meant to do.
Specialized Cells
We have many different types of cells. Each has its own function. They have physical and chemical differences that are suited to their functions. I.e. Muscle cells use a lot of energy, therefore they contain many mitochondria.
Red Blood Cell Structure
• have a depression to increase surface area to carry more oxygen
• contains the oxygen-transporting pigment, hemoglobin
• do not have a nucleus (or mitochondria or any other organelles)
Red Blood Cell Function
• function take-up, transport, and release of oxygen to the tissues
• small amount of CO2 transport. Lack of organelles crates more space for oxygen transport.
Leukocytes (White Blood Cells) Structure
• highly mobile and capable of amoeboid movements (using cytoplasm to “crawl” along surfaces)
• Phagocytic- engulfs foreign or dead cells
Leukocyte Function
• seeks out and destroys microbes inside body (fight off disease and infection)
• able to squeeze through tight spaces to reach the site of infection (fewer of these than red blood cells, much larger than red blood cells)
Platelet Cells
• cause blood clotting
• fewer than white blood cells, smallest blood cells
Human Muscle Cells Structure
• muscle cells are long and thin, which allows them to change size easliy
Muscle Cells Structure
• cylindrical shape with banded myogibrils
• capable of contraction (shortening)
Muscle Cells Function
• move voluntary muscles acting on skeleton
Sperm Cell Structure
• motile (moved spontaneously), flagellated (has a tail like structure) cell with mitochondria
• nucleus forms a large proportion of the cell
Sperm and Egg Cell Function
• male gamete for sexual reproduction (sperm)
• female gamete for sexual reproduction (egg)
• mitochondria in sperm provide the energy for motility
Human Nerve Cells
• nerve cells have long extensions that carry messages a long distance
• carry these messages using electrical impulses
Human Fat (adipose) Cells Structure
• spherical cell with a large fat-filled vacuole
• nucleus pushed to the cell edge
Human Fat (adipose) Cells Function
• fat storage- cell fill entirely with fat
Human Skin Cells
• first line of defense for your body against “invaders”
• overlap to make it difficult for foreign objects to enter the body
Systems- Levels of Organization
• all organisms and their structure and function can be broken down into different levels of organization
• these levels begin at the simplest point, then become more complex as we move through the system of organization
Levels of Organization- Level 1- Cells
• are the basic unit of structure and function in living things
• may serve a specific function within the organism
• examples- blood cells, nerve cells, bone cells, etc