Molecules of Life Biology Lecture Flashcards
4 macromolecules
carbohydrates
lipids
proteins
nucleic acids
polysaccharides in bacterias (4) (4)
- capsules are formed from complex polysaccharides
- glycogen or levan are storages for polysaccharides
polysaccharides in plants (4) (4)
- cell walls are comprised of cellulose and pectins,
- starch is a storage form
polysaccharides in insects and fungi
exoskeletons and cell walls contain chitin
three types of lipids (4)
phospholipids - components of cell membranes
waxes - coat surfaces of plants and the skin of animals to prevent water loss
complex lipids - signaling molecules, photoreceptors, hormones, pigments, and vitamins
proteins
proteins - ubiquitous components of cellular structures
amino acids form proteins
most enzymes are proteins
protein function include - hormones, defence molecules, signalling molecules
nucleic acids
information storage molecules, DNA forms chromosomes in all prokaryotic cells, and in nuclei, mitochondrial and chloroplast organelles of eukaryotes
monomer of carbohydrate
monosaccharide
what is a monomer
what is a polymer
polymer of carbohydrate
polysaccharide
monomer of nucleic acid (4)
nucleotide
polymer of nucleic acid (4)
DNA strand
monomer of protein
amino acid
polymer of protein
polypeptide chain
monomer of lipid
fatty acid
polymer of lipid
triglyceride
nucleotides are the buiilidng blocks of nucleic acids
nucleic acids are polymers of nucleotides (sugar, phosphate, and nitrogenous base)
define double helix of DNA
DNA encodes information for the amino acids sequence of proteins
double helix - two polynucleotide strands connected by hydrogen bonds
how is RNA different to DNA
ribose instead of deoxyribose
include the base uracil instead of thymine
RNA uses info in DNA to specify sequence of amino acids in proteins
what does DNA replication require
- something to copy - parent strand of DNA
- something to do the copying - Enzymes
- Building blocks to make copy
nucleotide triphosphates
define elongation step of DNA replication
new strands of DNA are synthesised by DNA polymerase
what are helicases (4)
Helicases - use energy from ATP to unwind DNA
what are Single-strand-binding proteins
Single-strand-binding proteins (SSBs) coat strands to keep
them apart
what does unwinding of DNA cause
Unwinding of DNA introduces torsional strain in the molecule
that can lead to additional twisting of the helix, called
supercoiling
Topoisomerases
Topoisomerases are enzymes that prevent supercoiling
what is DNA gyrase function
DNA gyrase is the topoisomerase involved in DNA
replication that relieves the torsional strain
directionality of DNA polymerase describe it cunt
DNA polymerase can only synthesize in the 5’-to-3’ direction
why is DNA antiparallel
Antiparallel nature of DNA means new DNA strands must be
synthesized in opposite directions
how is leading strand synthesised
Leading strand synthesized continuously from an initial
primer
what is lagging strand synthesised
Lagging strand synthesized discontinuously with multiple
priming events
what are okazaki fragments
DNA fragments on the lagging strand are called Okazaki
fragments, must be connected together
why is eukaryotic replication more complex than prokaryotic (4)
larger amount of DNA in multiple chromosomes
linear structure (versus circular structure)
need to deal with ends (telomeres)
techniques within biotechnology
Biotechnology started with the ability to manipulate DNA
including:
Cutting at sequence specific sites
* Ligating DNA fragments together
* Amplifying DNA as plasmids in bacteria
* Separating and visualising DNA
restriction endonucleases
Enzymes that cleave DNA at specific sites
Used by bacteria against viruses
Discovery of restriction endonucleases important because of
their:
Ability to cut DNA into specific fragments
*
Use in gene cloning
DNA ligases (4) (4)
DNA ligase joins two DNA fragments forming a stable DNA
molecule
Catalyzes formation of a phosphodiester bond between
adjacent phosphate and hydroxyl groups of DNA
nucleotides
Same enzyme joins Okazaki fragments on lagging strand
in replication
Recombinant DNA replication (4)
Recombinant DNA can be stably replicated using a host
organism, often E. coli
.
Add DNA fragment of interest to a bacterial plasmid
*
Introduce plasmid to E. coli
Bacteria will incorporate recombinant DNA into genome
where it will replicate and be maintained for study
gel electrophoresis
Allows separation of DNA fragments by size
Gel made of agarose or polyacrylamide
Submersed in buffer that can carry current
Subjected to an electrical field
*
Negatively-charged DNA migrates towards the positive
pole
.
Larger fragments move slower, smaller move faster
DNA is visualized using fluorescent dyes
DNA fragments can be cut from gel and purified for use in
making recombinant DNA
what are sister chromatids (4)
when chromosome gets copied, you get two copies of each chromatid, these are sister chromatids
Time it takes to complete a cell cycle varies greatly
Fruit fly embryos = 8 minutes
Mature cells take longer to grow
* Typical mammalian cell takes 24 hours.
* Liver cell takes more than a year.
Growth occurs during G1, G2, and S phases
* M phase takes about an hour.
Most variation in length of G
Three Checkpoints of cell division (4) (4)
- G/S checkpoint
Cell “decides” to divide.
Primary point for external signal influence.
2.
G/M checkpoint
Cell makes a commitment to mitosis.
Assesses success of DNA replication.
3.
Late metaphase (spindle) checkpoint
Cell ensures that all chromosomes are attached to the
spindle.
Cyclin-Dependent Kinases (Cdks)
Cyclin-Dependent Kinases (Cdks)
Enzymes that phosphorylate proteins
* Primary mechanism of cell cycle control
Cdks partner with different cyclins at different points in the
cell cycle
Cdk-Cyclin Complex
Cdk - cyclin complex
Also called mitosis-promoting factor (MPF).
Activity of Cdk is also controlled by the pattern of phosphorylation
Phosphorylation at one site (red) inactivates Cdk.
Phosphorylation at another site (green) activates Cdk.
Control in Multicellular Eukaryotes
- Multiple Cds control the cycle as opposed to the single
Cdk in yeasts
Animal cells respond to a greater variety of external
signals than do yeasts, which primarily respond to signals
necessary for mating
More complex controls allow the integration of more input
into control of the cycle
what is cancer
unrestrained, uncontrolled growth of cells
failure of the cell cycle
