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chapter3: The Chemical Basis of Life:Organic Molecules :star: - Coggle…
chapter3: The Chemical Basis of Life:Organic Molecules :star:
formation and breakdown of organic molecules & macromolecules
condensation or dehydrations
a molecule of water is removed each time a new monomer is added "dehydration"
dehydration is catalyzed by enzymes
hydrolysis
a molecule of water is added back each time a monomer is released.
hydrolysis is catalyzed by enzymes
the carbon atom and organic molecules
organic molecules are abundant in
living organisms
Chapter 4 :General Features of Cells
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The Nucleus and Endomembrane System
Network of membranes enclosing the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles. Also includes plasma membrane. May be directly connected to each other or pass materials via vesicles. Boundary between the cell and the extracellular environment.
Plasma membrane
Functions:
-Membrane transport in and out of cell, with selective permeability. -Cell signaling using receptors. -Cell adhesion
Chapter 05: Membrane Structure, Synthesis and Transport
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Ways to move across membranes
Passive transport:
Requires no input of energy – down or with gradient
Passive diffusion – Diffusion of a solute through a membrane without transport protein
Facilitated diffusion – Diffusion of a solute through a membrane with the aid of a transport protein
Active transport
Requires energy – up or against gradient
Fluid-mosaic model
Membrane is considered a mosaic of lipid, protein, and carbohydrate molecules
Membrane resembles a fluid because lipids and proteins can move relative to each other within the membrane
Membrane Transport
The plasma membrane is selectively permeable
Allows the passage of some ions and molecules but not others.
This structure ensures that: -Essential molecules enter - Metabolic intermediates remain - Waste products exit
Synthesis of Membrane Components
Synthesis of Lipids
In eukaryotes, the cytosol and endomembrane system work together to synthesize lipids - Fatty acid building blocks are made via enzymes in cytosol or taken into cells from food - Process occurs at cytosolic leaflet of the smooth Endoplastic Reticulum (ER)
Synthesis of Transmembrane Proteins
Except for proteins destined for semiautonomous organelles, most transmembrane proteins are directed to the ER membrane first
From the ER, membrane proteins can be transferred via vesicles to other membranes of the cell
Fluidity of Membranes
Membranes are semifluid
Most lipids can rotate freely around their long axes and move laterally within the membrane leaflet. But “flip-flop” of lipids from one leaflet to the opposite leaflet does not occur spontaneously
Flippase requires ATP to transport lipids between leaflets
Transport Proteins
Transport proteins are transmembrane proteins that provide a passageway for the movement of ions and hydrophilic molecules across membranes. Two classes based on type of movement Channels
Transporters
Channels
Form an open passageway for thedirect diffusion of ions or molecules across the membrane. Most are gated example: Aquaporins. Also known as carriers Conformational change transports solute across membrane
Transporters
Principal pathway for uptake of organic molecules, such as sugars, amino acids, and nucleotides
Membrane Structure
The framework of the membrane is the phospholipid bilayer
Phospholipids are amphipathic molecules Hydrophobic (water-fearing) region faces in Hydrophilic (water-loving) region faces out
Membranes also contain proteins and carbohydrates The two leaflets (halves of bilayer) are asymmetrical, with different amounts of each component
Exocytosis and Endocytosis
Used to transport large molecules such as proteins and polysaccharides.
Exocytosis:
Material inside the cell packaged into vesicles and excreted into the extracellular medium
Endocytosis: Plasma membrane invaginates (folds inward) to form a vesicle that brings substances into the cell. Three types of endocytosis: Receptor-mediated endocytosis Pinocytosis: bringing inside the cell any liquid material Phagocytosis: bringing inside the cell any solid material
The Cytosol
Region of a eukaryotic cell that is outside the cell organelles but inside the plasma membrane.
cytoplasm includes everything inside the plasma membrane: cytosol - endomembrane system - semiautonomous organelles
Protein Sorting to Organelles
: Eukaryotic proteins are sorted to the right destination:
Cotranslational sorting:
For ER, Golgi, lysosomes, vacuoles, plasma membrane, and secreted proteins
Begins in cytosol during translation
Involves sorting signals and vesicle transport
Post-translational sorting:
Most proteins for nucleus, mitochondria, chloroplasts,and peroxisomes
synthesised in cytosol and sorted later
Overview of Cell Structure: two categories of life
Prokaryotes:
Simple cell structure - No nucleus
Archaea:
- Also small cells, 1 μm – 10 μm in diameter - Less common - Often found in extreme environments
Bacteria:
- Small cells, 1 μm – 10 μm in diameter - Very abundant in environment and our bodies. -Vast majority are not harmful to humans -Some species cause disease
Eukaryotes:
- More complex cells - DNA enclosed within membrane bound nucleus. -Internal membranes form organelles
Semiautonomous Organelles
Mitochondria and chloroplasts:
Mitochondria
: -Primary role is to make ATP -Outer and inner membrane .Intermembrane space and mitochondrial matrix -Also involved in the synthesis, modification, and breakdown of several types of cellular molecules -Contain their own DNA, divide by binary fission.
Chloroplasts:
Photosynthesis: Capture light energy and use some of that energy to synthesize organic molecules such as glucose. -Found in nearly all species of plants and algae -Outer and inner membrane :Intermembrane space. Thylakoid membrane. -Contain their own DNA, divide by binary fission
Chapter 8: Photosynthesis
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Photosynthetic pigments
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Molecular Features of Photosystems
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Reactions That Harness Light Energy
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Synthesizing Carbohydratesvia the Calvin Cycle
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Photosynthesis
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Variations in Photosynthesis
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Grow and divide to reproduce themselves. They are not completely autonomous because they depend on the cell for synthesis of internal components100
cell theory
All living organisms are composed of one or more cells.
Cells are the smallest units of life. New cells come only from pre- existing cells by cell division.
macromolecules are large, complex organic molecules
organic molecules contains carbon
carbon has 4 electron in its outer shell, it needs 4 more electrons to fill the shell
it can make single or double bonds
can form polar (water soluble) and non polar (not water soluble)
functional groups
: groups of atoms with special chemical features that are functionally important. each type of functional group exhibits the same properties in all molecules in which it occurs.
isomers
: 1) structural isomers: same atoms but different bonding relations
2) stereoisomers: a) cis-trans isomers b) enantiomers
4 major types of organic molecules and macromolecules
lipids
They are non polar. most of the carbon atoms in a carbohydrates are linked to a hydrogen atom and a hydroxyl group
fats
phospholipids
steroids
waxes
proteins
carbon, hydrogen, oxygen, nitrogen, and small amount of other elemnt. building blocks of broteins are amino acid. 20 different amino acids
secondary
tertiary
primary structure
quaternary
carbohydrates
-Composed of carbon, hydrogen, and oxygen atoms.
-Most of the carbon atoms in a carbohydrate are linked to a hydrogen atom and a hydroxyl group
monosaccharides
disaccharides
polysaccharides
nucleic acids
responsible for the storage, expression, and transmission genetic information. monomer is nucleotide.
RNA: decodes DNA into instructions for linking together a specific sequens of amino acids to form a polypeptide chain
DNA: stores genetic information encoded in the sequence of nucleotide monomers.
Chapter 11:
Nucleic Acid Structure, DNA Replication, and Chromosome Structure :star:
An Overview of DNA Replication
Late 1950s – three different models were proposed for DNA replication: Semiconservative Model - Conservative Model - Dispersive Model
Newly-made strands are “daughter strands”
Original strands are “parental strands
Molecular Mechanismof DNA Replication
Origin of replication provides an opening called a replication bubble that forms two replication forks
DNA replication proceeds outward from forks
Bacteria have single origin of replication / Eukaryotes have multiple origins of replication
Biochemical Identification of the Genetic Material
What is the genetic material? Four criteria necessary for genetic material:
Information
Replication
Transmission
Variation
Three levels of DNA compaction
30-nm fiber Current model suggests asymmetric, 3D zigzag of nucleosomes Shortens length another 7-fold
DNA wrapping DNA wrapped around histones to form nucleosome Shortens length of DNA molecule 7-fold
Nucleic Acid Structure
Levels of DNA Structure:
Nucleotides – the building blocks of DNA and RNA
Strand – a linear polymer strand of DNA or RNA Double helix – the two strands of DNA
Chromosomes – DNA associated with an array of different proteins into a complex structure
Genome – the complete complement of genetic material in an organism
Molecular Structure of Eukaryotic Chromosomes
Typical eukaryotic chromosome may be hundreds of millions of base pairs long. Length would be 1 meter. But must fit in cell 10-100μm
Chromosome
Discrete unit of genetic material
Chromosomes composed of chromatin DNA-protein complex