EK B1 Ch1 Biological molecules Flashcards
glycine
- smallest amino acid, contains a hydrogen atom as the side chain- contributes to the structure n function of proteins-necessary for the synthesis of heme, an iron-containg molecule required for hemoglobin function in red blood cells
glutamate, and derivatives of amino acid tyrosine
- are important for signalng molecules in the brain and function as neurotransmitters
glutamine and alanine
- required for metabolic pathways involved in nitrogen metabolism
amphipathic molecules
polar and nonpolar chemical properties contained within the same moleculefatty acids - consist of carobxyl group (polar) attached to an end hydrocarbon chain (nonpolar)
fatty acids in living cells primarily act…..
as components of plasma membrane lipids, which form a hydrophobic barrier separating the aqueous phases of the inside and outside of cells.
saturated fatty acids
have NO C=C double bonds in hydrocarbon chain
unsaturated fatty acids
have C=C double bonds
phospholipids
The most abundant lipids in cell membranes are phospholipids, which generally contain a simple organic molecule attached to a negatively charged phosphoryl group and two fatty acids. Besides the plasma membrane, eukaryotic cells (plant and animal cells) contain a variety of intra- cellular membranes consisting of fatty acid–derived lipids. These include the nuclear membrane, the inner and outer mitochondrial and chloroplast membranes, and mem-branes associated with the endoplasmic reticulum and Golgi apparatus
ATP levels…
ATP levels inthe cell are a measure of available energy because a large number of biochemical reactions depend on phosphoryl transfer energy made available from ATP hydrolysis.
triacylglycerols
Another important function of fatty acids in eukaryotes is as a storage form of energy, which is made possible by their highly reduced state. Fatty acids yield chemical energy upon oxidation in mitochondria. Used for energy storage in this way, fatty acids are converted to triacylglycerols and sequestered in the adipose tissue of animal cells, whereas plants store triacylglycerols in seeds. Triacylglycerols are neutral (uncharged) lipids that contain three fatty acid esters covalently linked to glycerol. Lastly, fatty acids and fatty acid–derived molecules have recently been shown to be important signaling molecules that bind to nuclear receptor proteins. In this way, fatty acids regulate lipid and carbohydrate metabolism, inflammatory responses, and cell development.
peptide bond
any of 20 different amino acids can be linked together by a covalent bond called a peptide bond (Figure 1.11). Polypeptide chains also have polarity, as they contain an amino group on one end and a carboxyl group on the other. Therefore, the number of octamer polypeptides that can theoretically be assembled with any one of the 20 amino acids at each position is a staggering 208, or 2.58 × 1010 different protein sequences. However, the actual number of different polypeptide sequences encountered biologically is much smaller than the theoretical number because not all combinations of amino acids have useful structural and functional properties due to differences in the size and chem- istry of their side chains.
Chitin
-is another abundant carbohydrate polymer found in nature, is a major component in the exoskeletons of many invertebrates (insects and crustaceans) and in the cell walls of some types of fungi. Chitin consists of repeating N-acetylglucosamine units, a derivative of glucose, linked together by the same type of β(1→4) glycosidic bonds found in cellulose. Many types of bacteria contain the enzyme chitinase, which is able to cleave the β(1→4) glycosidic bond in chitin and thereby facilitate decomposition processes.
The polysaccharides amylose and cellulose contain….
…..the same repeating unit of glucose,but differ in the structure of the glycosidic bond linking adjacent units (shown in red). p. 15 a. Amylose (starch) is a polymer of glucose containing α(1→4) glycosidic bonds between glucose units.b. Cellulose, contained in plant cell walls,is identical in composition to amylose; however, the glycosidic bonds between glucose units arein the β(1→4) configuration,and adjacent glucose residuesare rotated 180°.
bacteria cell wall
The bacterial cell wall itself is coated with either a capsule or a slime layer that aids in enabling the bacterium to attach to other cells or solid surfaces.
bacteria cytoplasm
The cytoplasm of the bacterial cell contains all of the enzymes required for cell metabolism, as well as the chromosome, which consists of DNA compacted with nucleic acid binding proteins to minimize its size.
bacteria chromosome
The bacterial chromosome is circular and localized to a region in the cell called the nucleoid.
bacteria cytoplasm
also contains proteins involved in cell division and the assembly of extracellular structures, such as flagella and pili, which are used for cell movement.
bacteria plasmid
Many types of bacteria contain one or more circular DNA molecules called plasmids, which may encode genes involved in cell mating or antibiotic resistance. The plasmid replicates independently of the bacterial chromosome. Recombinant DNA methods make use of bacterial plasmids for gene cloning.
what is the size of eukaryotic cells versus prokaryotic cells
Note that the diameter of eukaryotic cells is as large as ∼10–100 μm, whereas the diameter of prokaryotic cells is only ∼1 μm. so eukaryotic cells are 10-100 times larger than most bacteria
Bacteria are prokaryotic cells with……
a cytosolic compartment surrounded by a plasma membrane that forms a barrier separating the cell from the environment. Most bacteria contain a single circular chromosome and move using flagellar structures or pili located on the outside of the cell.
Animal cells differences/ what makes them special
Animal cells are a type of eukaryotic cell and contain numerous intracellular membrane-bound compartments, which create microenvironments for biochemical reactions. Membrane-bound organelles in all types of eukaryotic cells include mitochondria, lysosomes, and peroxisomes, which are subcellular sites for specific metabolic reactions. ** why they are on the outside**
Plant cell differences/ what amkes them special
Plant cells are eukaryotic cells that contain chloroplasts, which convert light energy into chemical energy by the process of photosynthesis.Plant cells also contain large vacuoles, which are responsible for maintaining metabolite pools. The plasma membrane of plant cells is surrounded by a cell wall consisting of cellulose, which provides structural integrity to the plant.vacuoles are very large membrane bound**remember Both mitochondria and chloroplasts contain their own genomic DNA, which encodes pro- teins required for organelle function. ***
chromatin (euk)
eukaryotic DNA is packaged with proteins to form a structure called chromatin that is contained within a membrane-bound region of the cell called the nucleous
nucleolus
which is where ribosomes are assembled from ribosomal RNA and protein
ribosomes
Ribosomes are large RNA–protein complexes that mediate proteins syntehsis in prokartyotic and eukartoic cells
ER
rough adn smooth–> which are highly invaginated membrane structures that sequester ribosomes for protein synthesis.
Golgi apparatus
is a membranous structure involved in protein translocation within the cell and in facilitating protein secretion at the plasma membrane.
mammalian macrophage cells
are protective cells in the immune system that seek out and destroy invading microorganisms or abnormal cells based on identification of foreign cell surface proteinsare immune cells in animals that engulf microorganisms such as bacteriaMicrophages use pseudopodia to recognize foreign or abnormal cells based on cell surface proteins
endosymbiotic theory
proposes that eukaryotic cells evolved about 1.5 billion years ago as a result of large predatory cells engulfing aerobic bacteria, which eventually gave rise to mitochondria. The symbiotic bacteria were able to use O2 in the atmosphere as an electron acceptor in oxidation–reduction reactions, which provided a form of chemical energy for the synthesis of ATP. The predatory cells benefited from the extra ATP produced by the symbiotic bacteria, which in turn were rewarded with a nutrient-rich environment. Supportive evidence for the endosymbiotic theory comes from DNA sequence similarities between mitochondrial and bacterial genomes that have been analyzed using computational methods.
liver
metabolic control center
skeletal muscle
mechanical work and glucose homeostasis
intestines
nutrient absorption
adipose tissue
energy storage and hormonal signaling
kidneys
water, nitrogen, and electrolyte balance
How does the molecule glucose fit into the seven hierarchical levelsthat define the chemical basis of life on Earth?
Glucose is a biomolecule that contains three of the most abundant elements in living systems: carbon, oxygen, and hydrogen. Amylose and cellulose are polymers of glucose, and glucose biosynthesis is maintained by highly regulated metabolic pathways. Glucose is the primary component of plant cell walls and can be stored for energy needs in plant and animal cells in the form of starch and glycogen, respectively. The circulatory systems of multicellular organisms, such as mammals, transport glucose between tissues, which primarily use this metabolite for energy conversion processes (glycolytic path- way to generate ATP). Flowers contain nectar, a rich source of glucose (and fructose), which is used by honeybees as a nutrient source; when honeybees retrieve nectar, they cross-pollinate plants to help build a healthy ecosystem.
nucleotides (the building blocks of nucleic acids) are made up of 3 THINGS
• a nucleotide base (adenine, guanine, cytosine, thymine, or uracil); • a five-carbon ribose or deoxyribose sugar• one or more phosphate groups.
Nucleotides are the building blocks of nucleic acids……. details about them
The common nucleotides in DNA and RNA contain a nucleotide base attached to the 1′-carbon of the ribose sugar and a phosphoryl group attached to the 5′-carbon. The 2′-carbon of ribonucleotides contains a hydroxyl group, whereas deoxyribonucleotideshave a hydrogen atom in this position.-G-C base pairs contain three hydrogen bonds.- A-T base pairs in DNA–DNA hybrids contain two hydrogen bonds. -A-U base pairs in DNA–RNA duplexes or RNA–RNA duplexes contain two hydrogen bonds. Hydrogen bonds are shown as dashed red lines between the base pairs.
key differences DNA vs RNA
Deoxyribonucleotides are the monomeric units of DNA and lack a hydroxyl group on the carbon at the 2′ position (C-2′) of the ribose sugar, whereas ribonucleotides in RNA contain a hydroxyl group in this same position. As originally proposed by Watson and Crick and later confirmed by high-resolution X-ray crystallography, the DNA double helix contains two single polynucleotide strands that interact noncovalently to form a duplex. These strands are noncovalently associated through hydrogen bonds between the nucleotide bases, forming a duplex structure. The deoxyribonucleotide base pairs in DNA consist of guanine hydrogen-bonded to cytosine (G-C or C-G base pair) and adenine hydrogen-bonded to thymine (A-T or T-A base pair)RNA lacks the nucleotide base thymine and instead contains the nucleotide base uracil, which hydrogen bonds with adenine (A-U or U-A base pair)Because the chemical structures of nucleic acids are very similar, hybrid molecules of DNA and RNA can form, provided they contain complementary nucleotide bases to form G-C, A-T, or A-U base pairs
hydrogen bond
Hydrogen bonds are a type of weak non-covalent interaction in which a hydrogen atom is shared between polar groups.
polarity of DNA strands
The polarity of each DNA strand is determined by the bonds between the ribose and phosphate groups, which form the sugar–phosphate backbone.Two antiparallel DNA strands are held in register relative to each other by the hydrogen bonds between the nucleotide base pairs.
How genome is copied….
- DNA replication2. DNA transcription
DNA replication
requires that DNA/genome be faithfully copied by a process called DNA replication and that segments of DNA, known as genes, be converted into RNA by DNA transcription. - so genome is copied during cell division by this process
DNA transcription
- genes are converted into RNA by DNA transcription. Genes are functional units of DNA that are defined by the RNA products they produce. A variety of RNA products are generated by DNA transcription, one of which is mRNA, which is used to synthesize proteins by mRNA translation. The majority of RNA produced by DNA transcription is required for protein synthesis (rRNA and tRNA), RNA processing (snRNA), and regulation of gene expression or protein synthesis (miRNA). Under some conditions, RNA molecules can also be converted back into DNA by reverse transcription.
mRNA
A subset of the gene-encoded RNA molecules are called messenger RNA (mRNA) molecules. These are used as templates for protein synthesis in a process referred to as mRNA translation.DNA sequences are transcribed into mRNA by the enzyme RNA polymerase in the nucleus of eukaryotic cells. RNA polymerase synthesizes mRNA using ribonucleotides that form complementary base pairs with deoxyribonucleotides in the template strand of DNA. -The DNA sequence of the coding strand is the same as the RNA sequence in the mRNA, with the exception of uridine replacing thymidine. -The mRNA is then exported to the cytoplasm, where it is translated into protein.
