Week 1 Pt 2 Flashcards
o Prokaryotes
Do not have a nucleus
• Chromosome is directly in the cytoplasm of the cell
Does not have organelles
Includes bacteria and archaea
o Eukaryotes
• Chromosomes are contained in a membrane bound nucleus
Elemnts
% of cells mass comes from only 4 elements
o Hydorgen
o Carbon
o Nitrogen
o Oxygen
- 0.9% comes from another 7 Na, Mg, K, Ca, P, S, Cl .
- Cell arrange these atoms in limitless ways to produce millions of unique molecules.
Molecules
- Individual atoms are assembled into small molecules by cells
o These become the building blocks for assembling larger macromolecules
4 major types of macromolecules form the bulk of cells:
• Carbohydrates (polysaccharides)
• Nucleic Acid (DNA and RNA)
• Proteins
• Lipids
Many genetic disorders are know to affect the metabolism of molecules in cells.
Carbohydrates
Functions
the sugars that we take up form our diet that can be later metabolized or modified
o Are made or only carbon, hydrogen and oxygen
o Typically contain 5-6 carbons
o Can be individual molecules or can be linked together to form disaccharides (2 sugar molecules together) and polysaccharides
Sucrose (table sugar) – disaccharide – glucose and fructose
Starch – polysaccharide – many molecules of glucose
o Energy sources and energy storage
o Can be linked to lipids and proteins to modify their properties
o Ribose is needed to make nucleotides
Nucleic Acids
Functions
- Primarily DNA and RNA
- Made of repeating units of nucleotides linked together
o Nucleotides are made of :
A sugar ( ribose or deoxyribose)
A base (Adenine, thymine, guanine, cytosine, or uracil-rna has this not not dna)
One or more phosphates
Functions
o Storage and transmission of genetic information
o Energy (ATP)
o Cell signaling.
Proteins
Functions
- Proteins perform the majority of the work that occurs in cells
o Produce the traits that are specific by a specific allele of a gene - Proteins are made of long chain individual amino acids linked together – the side chain is what makes them different.
o There are 20 standard amino acids used to make proteins in humans and other organisms
Each amino acid is specified in a gene by a sequence of 3 nucleotides in DNA
Amino aids differ from one another based on the chemical groups that form the side chain
• Each side chain has unique chemical properties. - Functional proteins are formed when the amino acid chain folds into a unique 3 dimensional shape
o Therefore, a genetic change in DNA can change the amino acid that is specified in protein. Changing the amino acid can change the 3D shape of the protein, which can change its function. This would be an example of a trait being altered. - Proteins come in all shapes and sizes, which are determined by the DNA sequence of their respective genes. Shape = function
- Proteins perform many different functions in the cell, including:
o Structure/ support
o Communication - hormones
o Transport
o Enzymes – if it’s wrong the wrong enzye will b produced.
Catalyze most of the chemical reactions that occur in cells
• Sources of many genetic disorders
Lipids
Lipids
- Diverse group of molecules composed mainly of carbon and hydrogen – proteins- traits , lipids = cells.
- Mainly hydrophobic (repel water) but may also have hydrophilic ( attract water) components.
- Several different types/ classes
o Phospholipids – major component of lipid bilayer that forms the membranes of cells
o Triacyglycerols – used to store energy I adipose tissue
o Sterols – ringed statures including cholesterol and hormones such as testosterone and cortisol.
- Eukaryote cell - 4 parts
Plasma membrane
Nucleus
Cytoplasm
Cytoskeleton
Plasma membrane
Functions
o Membrane is barrier for all polar atoms and molecules –the is what keeps it alive when a cell dies and if It cannot maintain this it dies and it all leaks out.
Only very hydrophobic molecules can pass through membrane
Allows cell to maintain specific chemistry
• Ion concentrations
• Concentrate nutrients
• Retains molecules and macromolecules inside cell
Allows communication
Allows movement
Each of organelles inside of a eukaryote has its own membrane to keep is separated, unlike a bacteria where its all swimming together.
- A bilayer (double layer) of tightly packed phospholipids that form cell boundary
o Phospholipids have two major components
Two hydorphobic fatty acid tails
A hydrophilic head containing a glycerol, a phosphate, and a polar head group ( sugar, amino acid, or other small molecules)
o Chemical properties of phospholipids allow them to self assemble isn’t membrane sheets in water
Hydrophobic tails orient themselves towards each other to repel water
Hydrophilic heads are attracted to water
o Membranes also contain a lesser amount of cholesterol and other lipids that give membranes specific properties.
- Membrane also contains proteins with specific functions
o Signal receptors receive signals from the environment and pass the information to the inside of the cell
o Transporters and channels allow th selective movement of molecules across the membrane
o Adhesion proteins allow cells to stick to each other or surfaces
Often also connected to cell cytoskeleton
o Membrane proteins often have sugar groups added to portions that are on the outside of cell
Allow self recognition
Attract water.
Nucleus
Functions
- Functions
o Stores cell chromosomes
- DNA
o Site of transcription
o Site of ribosome synthesis - Structure
o Separated from the rest of cell by nuclear envelope
Two layers of lipid bilayer with small. Space between them.
Contains pores that allow bio chemicals to pass between cytoplasm and nucleus
Has own cytoskeleton proteins call lamins
• Provide shape and support
• May help organize chromosomes
Nucleolus
• Dark spot in microscope is area of ribosome synthesis
Cytoplasm
Functions
- Everything else In a cell that is inside the plasma membrane but outside of the nucleus
- Gel-like material filled with proteins, small molecules and organelles
o Site of many biochemical reactions including sugar metabolism
o Site of protein synthesis (translation) by ribosomes
o Several different membrane bound organelles with specific functions
Localizes related chemical reactions/ processes
Protects rest of cells from damaging reactions
o Endoplasmic reticulum (ER)
Large system of membranes continuous with nuclear envelope
Start point for trafficking of proteins ad lipids to the plasma membrane, other organelles or outside of cell
Materials move between organelles in vesicles
• Membrane bound sac
Rough ER
• Ribosome attached to ER
o Proteins are simultaneously synthesized and inserted into ER
Provides quality control
• Proteins cannot leave ER unless properly folded and processed
o Golgi Apparatus
Stack of membranes for Further processing of proteins form the ER and synthesis of materials
Carbohydrates are synthesized and added to proteins or included into vesicles
Packing of materials into vesicles
• Providing routing of vesicles destined for various places in the cell.
o Secretion
Materials destined for plasma membrane outside of cell follow a defined route
• Ex. – Protein hormones such as insulin
o Milk , membrane proteins
When vesicles reaches plasma membrane
• Soluble components are released to environment
• Components of vesicle membrane are integrated into plasma membrane
Genetic errors that cause protein folding or processing mistakes can inhibit this process
• Ex- cystic fibrosis
- Intracellular digestion
o Organelles devoted to removing unwanted materials from cells • Aged/ defective proteins • Defective organelles • Materials from environment 1. Lysosomes 2. Peroxisomes
o Lysosomes
Contain 43 enzymes to degrade proteins, lipids and sugars
Missing enzymes can lead to lysosomal storage diseases
• Ex- Tay-Sachs
Acidic environment
o Peroxisomes
Also contains specific enzymes for digestion and detoxifying cells
Segregates peroxides from rest of cell – reactions ivoloving oxygen
Also has associated genetic diseases
• EX- Adrenoleukodystrophy
o Mitochondria
Produces majority of cells energy
• Food is broken down in cells and converted to ATP by mitochondria
Usually 100’s and 1000’s per cell
Double membrane ( inner and outer)
Inner membrane is highly folded into cristae
• Increases surface area
Has own DNA- only one
• Contains 37 genes in humans
• Has separate pattern of inheritance from nuclear DNA – comes only from mother
• Has associated genetic diseases.
o Cytoskeleton
Meshwork of protein filaments that provide structure, support, and other functions
- Microtubules
- Microfilaments
Microtubules
• Hollow tubes made of individual tubulin proteins • Functions o Separate chromosomes during mitosis o Movement of organelles and vesicles o Structure of cilia and flagella.
Microfilaments
• Polymer of actin proteins • Mainly found underlying plasma membrane • Functions o Mechanical strength o Contraction/ movement • Intermediate filaments o Long “cable – like ‘ fibers of intertwined proteins Ex- Keratin, Lamins(Nucleus) o Functions Mechanical strength Provide connections between cells
