Cellular Level of Organization Flashcards
What is the basic unit of all living things?
- cells
What are cells composed of?
- atoms and molecules
What are prokaryotic cells?
- simple cells that have no nucleus
- most are unicellular bacteria
- our bodies do contain many of these cells
What are eucaryotic cells?
- cells that are complex with a nucleus and sub cellular structures (organelles)
- fungi plants and animals are eukaryotes
What are the three components of eucaryotic cells?
- plasma membrane
- cytoplasm
- nucleus
What is the job of the plasma membrane in eucaryotic cells?
- The membrane is a selectively permeable barrier separating the internal and external environment
- regulation, selectivity, communication
What is the purpose of the cytoplasm in eukaryotic cells?
- The cytoplasm contains cellular contents between the plasma membrane and nucleus
What is the purpose of the nucleus in eukaryotic cells?
- contains the genetic library of the cell (DNA)
What are the components of the cytoplasm?
- cytosol - the fluid portion
- intracellular fluid
- water, dissolved, and suspended particles
- organelles
What are the hereditary units called?
- genes
What is the purpose of genes?
- Control most aspects of cell structure and function
Explain the plasma membrane as a semi permeable regulator.
- covers and protects the cell
- Controls my cousin comes out
- links to other cells
- Fly certain flags to tell other cells who it is
What is a fluid mosaic model?
- A representation for the arrangement of molecules within the membrane
Explain the properties of the fluid mosaic model.
- likes a continuously moving sea of lipids containing a mosaic of proteins
What is the purpose of lipids in the fluid mosaic model?
- The lipids act as a barrier to certain substances and passage of lipid soluble molecules
What is the purpose of proteins in the fluid mosaic model?
- proteins act as a gatekeepers, allowing passage of specific molecules and ions
- some flow freely, others are anchored
What are the four components in regards to the structure of the plasma membrane?
- phospholipids, integral proteins, transmembrane proteins, peripheral proteins (4)
What is the purpose of phospholipids in regard to the structure of the membrane?
- form of bilayer – cholesterol and glycolipids also contribute
What is the purpose of Integral proteins in the structure of the membrane?
- they extend into or through the bilayer
What is the purpose of transmembrane proteins?
- span the entire lipid bilayer
- are amphipathic just like the phospholipids
What do the peripheral proteins in the plasma membrane do?
- attached to the inner outer surface but do not extend through the membrane
Explain the bilayer arrangement of the plasma membrane.
- two back to back layers of phospholipids
- The head faces water on the inside and outside of the cell
What are glycoproteins?
- membrane proteins with a carbohydrate group attached that protrude into the extracellular fluid
What is the Glycocalyx?
- The entire sugary coating surrounding the membrane
- help cells recognize each other to prevent attack
What is another function of the glycocalyx?
- enables white blood cells to detect for an organism,
- allows cells to adhere to one another
- protects cells from enzymes in the extra cellular fluid
Is the glycocalyx hydrophobic or hydrophilic?
- hydrophilic
- it attracts fluid to the surface of the soul making red blood cells slippery
What are the functions of the plasma membrane in regard to ion channels?
- allow specific ions into or out of the cell
What are the functions of the plasma membrane in regard to carriers?
- selectively move substances through the membrane by changing shape - aka transporters
What are the functions of the plasma membrane in regard to receptor?
- bind to specific molecules (ligand) and then alter the cells functions.
What are the functions of the plasma membrane in regard to enzymes?
- catalyze chemical reactions inside or outside cell
- Others act as cell-identity markers (glycoproteins and glycolipids)
What are linkers in the plasma membrane?
- anchor filaments inside and outside the plasma membrane
- provide structural stability and shape
Membrane fluidity depends on what?
- the bends in the fatty acids of the phospholipids and presence of cholesterol
- ** more bends increases the fluidity
What does membranes fluidity enable?
- allows for some mobility
- maintaining organization and structural organization
- allows for membrane to self seal pictured
- allows for formation of cellular junctions
What is selective permeability?
- membrane allow some substances across but not others
What type of molecules are typically allowed to cross a selective permeable membrane?
- small, neutrally charge, lipid soluble substances can freely pass
Why can water (which is polar) freely pass a selective permeable membrane?
- because of its small size
What is the purpose of Chad‘s membrane proteins?
- They act as channels and transporters
- assistant entrance of certain substances that can’t pass through the membrane themselves
Is there inner cell surface positively or negatively charged?
- negatively charged
Is the outer cell surface positively or negatively charged?
- positively charged
Electrical gradients are specific to what?
- The type of molecule
What are passive transport processes?
- substances moving across the cell membrane without the input of any energy
- down concentration or electrical gradient
What are active transport processes?
- Involve the use of energy, primarily from the breakdown of ATP
- move a substance against its gradient
What are some examples of passive transport processes?
- simple diffusion of a solute
- Diffusion of water (osmosis)
- facilitated diffusion
What are some examples of active transport processes?
- primary and secondary transport
- vesicular transport
What is the diffusion?
- The passive spread of particles through random motion, from areas of high concentration to areas of low concentration
What affects diffusion?
- The amount of substance and the steepness of the concentration gradient
- temperature
- mass of diffusion substance
- surface area
- diffusion distance
What is simple diffusion?
- A passive process that occurs when substances move through the lipid bilayer
- high concentration to low concentration
- without transport of proteins
What type of molecules move through simple diffusion?
- Nonpolar, hydrophobic molecules, or very small polar molecules
- o2, co2, fatty acids, steroids, fat soluble vitamins, water
What is channel mediated facilitated diffusion?
- A process worry solute moves down the concentration gradient through a membrane channel
Explain gated channels.
- most are ion channels
- Gates may operate at random or may be mediated by electrical or chemical changes
- Number of ion channels varies by cell
What is an example of channel mediated facilitated diffusion?
- The passage of potassium ions through a gated K+ channel
What is carrier mediated facilitated diffusion?
- passive diffusion process where a care of your protein moves I saw you down in concentration gradient
Explain how a solute moves through carrier-mediated facilitated diffusion.
- A solute binds to a carrier on one side of the membrane and is released on the other side when the carrier change shape
What is an example of carrier mediated facilitated diffusion?
- The passage of glucose across the cell membrane
What is osmosis?
- The net movement of solvent through a selective permeable membrane
- from an area of high concentration to an area of lower concentration
Osmosis only occurs when….
- A membrane is permeable to a solvent and not a solute
What are the two ways water can pass through the plasma membrane?
- through lipid bilayer by simple diffusion
- through aquaporins (integral membrane proteins)
What is osmotic pressure?
- The pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis
Is pressure of the side is all equal to osmotic pressure of extra cellular fluid?
- yes, they are equal
What happens when a cell is placed in a solution with different osmotic pressure?
- The shape and volume of the cell change
What are the two components of the cytoplasm?
- cytosol and the organelles
What is a cytosol?
- Intracellular fluid surrounding the organelles
- 75 to 90% H2O
- Site of many chemical reactions
What is a cytoskeleton?
- network of protein filaments throughout the site is all
- provides structural support for the cell
What are the three types of protein filaments throughout the cytosol?
- microfilaments, intermediate filaments, microtubules
Explain the structure of microfilaments.
- thinnest
- most actin and myosin
- near edge of the cell
Explain the structure of intermediate filaments?
- do not participate in cell motility
- named for relative thickness
Explain the structure of microtubules?
- thick, long, unbranched and hollow
What is the centrosome?
- located near the nucleus
- consists of two centrioles and pericentriolar material
What is the cilia?
- Short, hair like projections from the cell surface
- move fluids along a cell surface
What are flagella?
- move the entire cell
- only example is the sperm cells tail
- majority of material is microtubules
What do ribosomes do?
- they are the sights of proteins synthesis made from mainly rRNA
How is a complete functional ribosome fabricated?
- made by assembling a large and small subunit
Where are ribosomes found?
- some are found attached to the endoplasmic reticulum
- free in the cell (proteins used by cytosol)
What is the endoplasmic reticulum?
- network of membranes in the shape of flattened sacs or tubules
Describe the rough endoplasmic reticulum.
- connected to the nuclear envelope
- consist of a series of flatten sacs
- surfaces studded with ribosomes
- produces various proteins
Describe the smooth endoplasmic reticulum.
- network of membrane tubules
- does not have ribosomes
- has enzymes are play a key role in the synthesis of fatty acids and steroids
- detoxification of certain drugs
Describe the Golgi complex
- consists of 3-20 flattened, membranous sacs called cisternae (stack of pancakes)
- cisterns on opposite sides vary in size, shape and enzyme activity
- cis (entry) face receives and modifies proteins from the rough ER
- enzymes modify (adds carbs and lipids to form glycoproteins and lipoproteins) in the medial cisternae
- sort and package proteins for transport to different destinations before release on the trans face (facing PM)
What are lysosomes?
- vesicles that form from the Golgi complex and contain powerful digestive enzymes that break down molecules within vesicles formed during endocytosis for use in the cytosol
- engulf other organelles, digest them and return components to cytosol (autophagy) or destroy the cell that contains them (autolysis)
What is autolysis?
- destruction of cells or tissues by their own enzymes
What is autophagy?
-
What is autophagy?
- conserved degradation of the cell that removes unnecessary components
What are peroxisomes?
- smaller than lysosomes
- detoxify several toxic substances (alcohol)
- abundant in the liver
What are proteasomes?
- continuously destroy unneeded, damaged, or faulty proteins
- found in the cytosol and the nucleus
- contain protease
Explain the anatomy of the mitochondria
Cristae - the series of folds of the inner membrane
Matrix - the large central fluid-filled cavity
- Have inner and outer mitochondrial membranes similar in structure to the plasma membrane
What are some features of mitochondria?
- Generate ATP through aerobic respiration
- Self-replicate during times of increased cellular demand or before cell division
- Contain own DNA
- Implications of mitochondrial biogenesis for exercise
- Have a role in apoptosis
Whew are the mitochondria located? Where are the enzymes catalyzed?
- Located within the cell where O2 enters or ATP is used
- Enzymes that catalyze cellular respiration are located on the cristae
Describe how the nucleus looks?
- Spherical or oval-shaped structure
Usually most prominent feature of a cell - nuclear envelope
- nuclear pores
What is the nuclear envelope?
- a double membrane that separates the nucleus from the cytoplasm
- out membrane is continuous with the endoplasmic reticulum
What are nuclear pores?
- numerous openings in the nuclear envelope made of a circular arrangement of proteins
- control movement of substances between nucleus and cytoplasm
What are the contents of the nucleus?-
- nucleoli
- genes
- chromosomes
What is the nucleoli?
- spherical body that produces ribosomes
- cluster of DNA, RNA and protein
What are genes?
- the cell’s hereditary units
control activities and structure of the cell - arranged along chromosomes
What are chromosomes
- long molecules of DNA combines with protein molecules
What is gene expression?
- the process by which genetic information encoded in DNA is used for synthesis of a protein
What is transcription?
- information encoded in a specific region of DNA is copied (transcribed) to produce RNA
What is translation?
- RNA attaches to a ribosome where the information in the RNA strand is translated into a corresponding amino acid sequence to form the new protein
What is a codon?
- specifies a particular amino acid - AUGT etc.
Describe the process of transcription. (How is it done)
- occurs in the nucleus
- genetic information encoded in DNA is copied onto a strand of RNA to direct protein synthesis
- only the part of the DNA that contains information for the specific/required protein is copied
Explain the process of transcription. (What is being created)
- three types can be made
- beginning at a promoter, RNA polymerase catalyzes transcription of one of the DNA strands
- ends at a terminator sequence where RNA polymerase is signaled to detach and RNA is released
