Unit 4: Cell Functions
Describe the cytoplasm and its function
-BOTH -clear gel-like fluid -home to the cell's organelles
Describe chloroplasts and their function
-PLANT CELLS ONLY -green, oval structures usually containing chlorophyll -captures energy from sunlight and uses it to produce food for cells
Define cancer
A disorder in which some of the body's own cells lose the ability to control growth.
Sister chromatids are attached to each other at an area called _____
Centromere
What are features of eukaryotes?
Eukaryotes are -cells that contain a nuclei -generally larger and more complex than prokaryotic cells -generally contains dozens of structures and internal membranes and are highly specialized -displays great variety -some live solitary lives as unicellular organisms while others form large multicellular organisms -includes plants, animals, fungi and protists`
What is passive transport?
It is the movement of material down the concentration gradient and it requires NO energy from the cell.
What is active transport?
It is the movement of material through a membrane AGAINST a concentration gradient, REQUIRES energy from the cell. (goes up concentration gradient)
What is exocytosis? (transport of large particles)
It is the process of expulsion or secretion of materials from a cell.
What makes up the cytoskeleton?
Microfiliments and microtubes.
What is osmosis?
Osmosis is diffusion of water through a selectively permeable membrane. Water is the only substance that carries out osmosis.
What are phospholipids?
They are in the cell membrane structure. They have lipids (fatty acids) with a phosphate group attached. They have a hydrophilic polar head and hydrophobic non-polar tails.
Draw the cell cycle.
cell cycle
Describe the mitochondria and its function
-BOTH -bean shaped with inner membrane -breaks down sugar molecules to create energy
golgi apparatus
-processes and packages substances for export from the cell -works closely with the ER in preparing materials for release from the cell -ships proteins off to their final destinations -completes final modification of proteins
cell membrane
-regulates the passage of materials into and out of the cells -consists of proteins and a phospholipid bilayer -may contain carbohydrates on the outer surface which are involved in cell recognition and cell joining -barrier that encloses the cell
What are chromatids?
Chromatids are copies of chromosomes. Each chromosome has 2 identical "sister" chromatid.
What are chromosomes?
Chromosomes are what carry the genetic information from one generation of cells to another. They are made up of DNA which carries the cell's coded genetic information. Humans have 46 chromosomes.
What is an isotonic solution?
Contains the same concentration of solute as another solution (e.g. the cell's cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. The fluid that surrounds the body of cells is isotonic.
How is the cell cycle controlled?
The cell cycle is regulated by a protein called cyclin. There are two types of regulatory proteins, those inside and those outside. (internal and external regulatory proteins) Cyclins control the timing of the cell cycle in eukaryotic cells.
What happens during the prophase?
The chromatin condenses into chromosomes. The centrioles separate and a spindle begins to from. The nuclear envelope breaks down.
What happens during the telophase?
The chromosomes gather at opposite ends of the cell and lose their distinct shapes. Two new nuclear envelopes will form.
What happens during the metaphase?
The chromosomes line up across the center of the cell. Each chromosome is connected to a spindle fiber at its centromere.
What problems does growth cause for cells?
The larger a cell becomes, the more demands the cell places on its DNA. In addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane. If a cell were to grow without a limit, an "information" crisis would occur.
What happens during the anaphase?
The sister chromatids separate into individual chromosomes and are moved apart.
What is the order of mitosis?
(Interphase), Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
Describe the golgi body and its function
-BOTH -flattened sacs or tubes -receives proteins and other materials from the ER and packages them and then redistributes them
Describe the vacuole and its function
-BOTH -fluid-filled sacs -storage area for cells
Describe the endoplasmic reticulum and its function
-BOTH -network of folded tubes or membranes (cristae and matrix located here ) -carries protein and other materials from one part of the cell to another
Describe the cell membrane and its function
-BOTH -plant: inside cell wall -animal: the outside layer -controls what comes in and out of the cell
Describe the nucleus and its function
-BOTH -rounded shape surrounded by rest of organelles -controls all of the cells activities
Describe ribosomes and their function
-BOTH -small bodies floating free or attached to the rough ER -produces proteins
Describe the cell wall and its function
-PLANT CELLS ONLY -Outer layer, rigid, strong, stiff, non-living -protects and supports cell -allows oxygen and water to pass through
Describe the lysosome and its function
-PLANT: uncommon -ANIMAL: common -small round structures -use chemicals to break down large food particles into smaller ones, and break down old cells
lysosome
-breaks down toxin and poisons -can digest old organelles and foreign substances such as viruses and bacteria -functions in "programmed cell death" to rid an organism of damaged or dead cells
Endoplasmic Reticulum (ER)
-consists of two types: rough and smooth -may or may not have attached ribosomes -receives polypeptides (proteins) from ribosomes to prepare protein for export or for insertion into membranes
nucleus
-controls the cells activities -contains a nucleolus which is responsible for manufacturing ribosomal subunits -the site where RNA is copied from DNA to direct protein synthesis -storage site ofDNA and genetic information
transport proteins
-found in plasma membrane (also known as carrier or channel proteins) -allows larger substances to move through the plasma membrane
cholesterol molecule
-helps stabilize the phospholipids -prevents the fatty acid chains of the phospholipids from sticking together
Hypertonic solutions
-high concentration of solute relative to another solution, water diffuses out of cell and the cell shrivels
phospholipids
-lipids (fatty acid) with a phosphate group attached -hydrophilic (likes water) head and hydrophobic (afraid of water) tail
Hypotonic solutions
-low concentration of solute relative to another solution, water diffuses into the cell and the cell swells and explodes
passive transport
-movement of material down the concentration gradient, requires NO energy from the cell
active transport
-movement of material through a membrane against a concentration gradient, requires energy from the cell
cytoplasm
-often called the cytosol -this area contains the various organelles of the cell -consists of a gelatin like watery fluid that contains salts, minerals, and many organic molecules and compounds
facilitated diffusion
-passive transport by proteins (NO energy required) channel proteins: form channels to allow specific molecules to flow through carrier proteins: change shape to allow a substance to pass through the membrane
cell wall
-rigid structures used for support in plants, algae, fungi, and many prokaryotes -found outside of the cell membrane in plants, much thicker than a cell membrane
Isotonic solutions
-same concentration of solute as another solution, water diffuses into and out of the cell at the same rate
the function of the cell membrane
-separates the components of a cell from its environment and surrounds the cell -selectively permeable and helps maintain homeostasis within the cell
ribosome
-site of protein synthesis -maybe found loose in the cytoplasm or attached to the ER -the most numerous organelles in most cells -the parts of this organelle are manufactured by the nucleolus in the nucleus -translates the message of MRNA and carries out the building of proteins
mitochondria
-the "powerhouse" of the cell -site of cellular respiration -transfers the energy stored in organic compounds (glucose) to molecules of ATP
transport of large particles: Exocytosis
-the expulsion or secretion of materials from a cell
osmosis
-the movement of water across a semipermeable membrane due to differences in the solute on each side
transport of large particles: Endocytosis
-the process by which a cell surrounds and takes in material from its environment (engulfed, creates vesicle)
difusion
-the random movement of molecules from an area of high concentration to an area of low concentration
chloroplast
-the site of photosynthesis -converts the energy of the sun into the chemical energy contained in molecules of glucose -found only in plant cells; may store pigments or food -contains the green pigment known as chlorophyll
vacuole
-the source of turgor pressure within a plant cell -a storage area found inside both plant and animal cells
What is a hypertonic solution?
A hypertonic solution is one where the concentration of solutes is greater outside the cell than inside it. When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to SHRIVEL
What is a hypotonic solution?
A hypotonic solution is one in which the concentration of solutes is greater inside the cell than outside of it. When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly EXPLODE.
What is a compound microscope?
A microscope that uses light ad lenses to magnify an object (lens magnifies an object x10)
Why can cancer be considered a disease of the cell cycle?
All cancers are a result of the control of the cell cycle being broken down. Some cancer cells will no longer respond to external growth regulators, while other fail to provide the internal regulators that ensure orderly growth.
What is the function of the cell membrane?
All cells have a cell membrane made of proteins and lipids. The cell membrane separates the components of a cell from its environment- surrounds the cell. It is the "gatekeeper" of the cell as it regulates the flow of materials into and out of the cell. It is selectively permeable meaning that it accepts certain things but not others. Cell membranes help maintain homeostasis (stable internal balance).
What is cell division?
Cell division is the process by which a cell divides into two new daughter cells. Before cell division occurs, the cell replicates/copies all of its DNA. This replication of DNA solves the problem of information storage because each daughter cell gets one complete set of genetic information. Cell division also solves the problem of increasing size by reducing cell volume as each daughter cell has an increased surface area to volume ratio.
What is cell specialization?
Cell specialization is the development of cells in different areas of an organism in order to perform different tasks.
What is cell transport?
Cell transport is movement of materials across cell membranes. Cell transport includes passive and active transport. Passive transport does not require energy whereas active transport requires energy to proceed. Passive transport proceeds through diffusion, facilitated diffusion and osmosis.
What is diffusion?
Diffusion is when particles move from an area where they are more concentrated to an area where they are less concentrated. Equilibrium is the condition that exists when the diffusion of a particular substance is complete.
What is facilitated diffusion?
Facilitated diffusion is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane. It is passive transport by proteins (no energy required) with -channel proteins which form channels to allow specific molecules to flow through -carrier proteins which change shape to allow a substance to pass through the membrane
What are transport proteins?
Found in the plasma membrane (aka carrier/channel proteins) they allow larger substances to move through the plasma membrane.
What is endocytosis? (transport of large particles)
It is the process by which a cell surrounds and takes in material from its environment . (engulfed, the cell membrane engulfs it and it will pinch off and make a vesicle)
What criteria would be useful for identifying plant and animal cells?
Plant cells are longer and more geometric. Animal cells are often separated.
What are features of prokaryotes?
Prokaryotes are -cells that do not have a nuclei -generally smaller and simpler than eukaryotic cells -have genetic material not enclosed with a nucleus -carry out activities associated with living things: they grow, reproduce, respond to the environment -includes bacteria
What are stem cells?
Stem cells are cells that serve as a reservoir of undifferentiated cells.
What is the cell theory?
The cell theory says that -all living things are composed of cells -cells are the basic units of structure and function in living things -new cells are produced from existing cells
What happens during cytokinesis?
The cytoplasm pinches in half. Each daughter cell receives an identical set of duplicate chromosomes.
What happens during the interphase?
The life of a cell as one cell division after another separated by an "in between" period of growth is called interphase. During this phase, the cell grows and replicates its DNA and centrioles.
What are the four levels or organization in multicellular organisms?
They are: individual cells, tissues, organs, and organ systems.
What do external regulators do in the cell cycle?
They direct cells to speed up or slow down the cycle.
What do cholesterol molecules do?
They help stabilize the phospholipids and prevent the fatty acid chains of the phospholipids from sticking together.
What do internal regulators do in the cell cycle?
They make sure that cells do not enter mitosis until chromosomes has been replicated. They also prevent cells from entering the anaphase until all of the chromosomes are attached to the mitotic spindle.