Frequent Mistakes Flashcards
At what C does galactose differ from glucose?
C4
At what C does mannose differ from glucose?
C2
How does fructose compare to glucose?
same as glucose but with a ketone group on C2
What is maltose?
2 glucose (alpha)
What is sucrose?
fructose + glucose (alpha)
What is lactose?
galactose + glucose (beta)
What kind of glycosidic linkages are not digesteable by humans?
Beta (opposite sides)
What is urea’s chemical structure?
H2N-C=O-NH2
What is a sphingolipid?
Sphingoside backbone + fatty acid chains + polar head group
What are the 4 types of sphingolipids?
- Ceramide
- Sphingomyelins = sphingophospholipids
- Glycosphingolipids
- Gangliosides
What are the 2 types of glycosphingolipids?
- Cerebrosides
2. Globosides
What is a sphingoside backbone?
Long C chain + HO-C-C-NH3-C-OH (with a double bond near the polar head group)
The NH3 is also bound to a O=C-R –> the fatty acid residue
What is a sphingomyelin? Does the head group have a net charge?
Sphingolipid with a phosphocholine group bound by a phosphodiester bond
Phosphocholine group = phosphatidylethanolamine or phosphatidylcholine
No net charge!
Is a glycosphingolipid a phosphosphingolipid?
No
Is a sphingomyelin a phosphosphingolipid?
Yes
What is a cerebroside? Does it have a net charge?
Glycosphingolipid with a single sugar as a head group
No net charge
What is a globoside? Does it have a net charge?
Glycosphingolipid 2 or more sugars as a head group
No net charge
What is a ganglioside? Does it have a net charge?
Sphingolipid with an oligosaccharide + 1 or more N-acetylneuraminic acid (NANA = sialic acid) as a head group
Yes, it is negatively charged
Is a ganglioside considered a glycosphingolipid?
Yes, because it has a glycosidic bond
What elements does a phospholipid contain?
Fatty acid tail + head: phosphate + alcohol
Linked by phosphodiester bonds
What is the difference between primary and secondary active transport?
Primary: requires ATP hydrolysis to move substances across their chemical gradients
Secondary: makes use of concentration gradients set up by primary active transport
What does a hydrolase enzyme do?
catalyze hydrolysis
What does a lyase enzyme do?
enzyme that catalyzes a catabolic reaction without water
What is facilitated diffusion? What molecules utilize this?
spontaneous passive transport → large, polar, and/or charged molecules through ion channels (proteins)
What is a nucleosidic bond?
bond between the nitrogenous base and the pentose sugar at the 1’ Carbon –> C-N bond forms
What bond forms in a peptide bond?
C-N
What is required for an amino acid to act as a buffer?
the pH needs to be near one of its pKas
What is the molecular weight of a peptide bond?
18
What kind of molecules will cluster around disulfide bonds?
HYDROPHOBIC molecules will cluster around disulfide bonds because they form the nucleus of the hydrophobic core of the folded protein.
Are allosteric interactions covalent?
No
Describe competitive inhibition
Km increases
Vmax stays the same
Lines intersect on the y-axis
Overcome by: increasing [S]
Describe noncompetitive inhibition
Km stays the same
Vmax decreases
Lines intersect on the x-axis
Overcome by: increasing [E]
Describe uncompetitive inhibition
Km decreases (due to better binding efficiency - prevent release of substrate = This makes it look like the substrate has greater affinity for the enzyme than it would otherwise, which lowers Km- as a result of Le Chatelier's principle and the effective elimination of the ES complex thus decreasing the Km which indicates a higher binding affinity). Vmax decreases (as a result of removing activated complex) Lines do not intersect, they are parallel
Described mixed inhibition
Km will increase or decrease (depending on binding affinity)
Vmax decreases
Lines will intersect at neither axis
Which is an organic molecule: coenzyme or cofactor?
Coenzyme
Can heat denature fatty acids?
NO
What 3 processes are endonucleases used for?
DNA repair, Southern blotting and gene therapy
What is proofreading? When does it happen? To whom? What is the key enzyme?
happens in the S phase for both prokaryotes and eukaryotes
fixes mismatched base pairs
key enzyme: DNA polymerase (distinguishes between strands thanks to methylation)
What is mismatch repair?When does it happen? What is the key enzyme?
happens in the G2 phase
fixes mismatched base pairs that were missed by the proofreading process
key genes: MSH2 and MLH1
What is nucleotide excision repair? When does it happen? What is the key enzyme?
happens in G1 and G2
repairs dimers
key enzyme: excision endonuclease
What is base excision repair? When does it happen? What is the key enzyme?
happens in G1 and G2
no double helix deformation (no base pair mismatch) but still not the base you want. ex: uracil inserted in DNA; take the one base out, then the whole thing and then reinsert the whole thing
key enzyme: glycosylase and AP endonuclease
What do primers do in PCR?
complementary to the DNA that attach at the 3’ end of each strand
What enzyme is involved in PCR?
DNA polymerase
What is Southern blotting?
: DNA is cut by restriction enzymes and then separated by gel electrophoresis → then DNA fragments are transferred to a membrane and probed with many copies of single stranded DNA sequences → probes are labeled and will indicate when they have bound to the complementary DNA strand
What happens during DNA sequencing?
uses ddNTPs → modified N+sugar nucleotides that contain a hydrogen at C-3’ rather than OH → once one of these bases is added, the polymerase can no longer add to the chain → sample will contain many fragments → separated by gel electrophoresis by size, so the sequence can then be read
Nucleotides vs nucleoside?
nucleoside = pentose + base nucleotide = nucleoside + phosphate group
3 Differences between prokaryotic and eukaryotic gene control?
Multiple transcription factors are necessary for eukaryotes
In eukaryotes RNA undergoes further modifications before translation
In eukaryotes, alternative splicing occurs so that multiple different proteins can be translated from the same primary message
1 similarity between prokaryotic and eukaryotic gene control?
both depend upon specific protein-DNA interactions
2 features of fatty acids found in eukaryotes?
EVEN number of Cs!
cis double bonds, never trans!
Effects of cholesterol on fluidity of plasma membrane?
At physio temperatures: increasing cholesterol content would decrease fluidity
At cold temperatures: increasing cholesterol would increase fluidity because it keeps the phospholipids from clumping together
From where does exhaled CO2 derive its O2?
from carbohydrates
What is the difference between synthase and synthesaze enzymes?
Synthase does not require outside energy
What does a dehydrogenase enzyme do?
transfers H- to an electron acceptor (NAD+, FAD, …etc.) → oxidizes its substrate
What does a reductase enzyme do?
reduces its substrate
What does a carboxylase enzyme do?
COOH is added to the molecule
What is the effect of uncouplers?
Uncouplers inhibit ATP synthesis without affecting the ETC, which means that the body will need to burn more fuel (like glycogen and use more O2) to maintain the H+ gradient!
Why is acetyl-CoA so energetic?
has very high energy thioester bonds.
Can acetyl-CoA be converted to glucose?
No!
Can fatty acids be converted to glucose?
Those with an odd number of Cs, yes!
What organ is most sensitive to O2 deprivation?
Brain
What kind of molecules are stored within the cell?
Polar
What is hyperplasia?
increased cell production in a normal tissue or organ.
What is an agonist?
binds to a receptor to increase what the receptor does; stimulate it
What does mitosis always produce?
Diploid cells
What is necessary for a gas to flow from one place to the other?
the partial pressure of the gas in the first place must be higher than that in the place it’s going to.
What is a test cross?
Always with a homozygous recessive genome
What does polymorphism mean?
phenotypic variations within the same species of the same population
What are the conditions for the Hardy Weinberg equilibrium? 5
- Large pop
- No mutations
- Random mating
- No migrations
- Equally successful genes
What did the Griffith experiment show?
bacteria can acquire new genetic material
What did the Avery-McLeod experiment show?
DNA is the genetic material (DNA degradation)
What did the Hershey Chase experiment show?
Confirmed DNA is the genetic material: radiolabeled DNA in infected bacteria
What is genetic leakage?
Flow of genes between species through hybrid offspring that are fertile
What is a monohybrid cross? What is the genotype ratio?
crossing 2 heterozygotes with complete dominance
1:2:1
What is hybrid breakdown?
2nd generation is inviable or sterile
What is gene flow?
gene flow (also known as gene migration) is the transfer of alleles or genes from one population to another
What is the basolateral membrane?
Faces toward the interstitium and away from lumen
What is the order from blood vessel to tissue?
Blood vessel Capillary endothelial cell Interstitium (with fluid) Basolateral membrane Epithelial cell Apical membrane Lumen
What is Mendel’s first law?
Segregation: alleles segregate during meiosis
What is Mendel’s second law? What is the problem with it?
Independent assortment
Problem: linked genes
Skeletal muscle: multi or uninucleated?
Multi
What are the differences between red and white muscle fibers?
Red: slow-twitch: carry out ETC
White: fast twitch: rely on anaerobic metabolism
Smooth muscle: multi or uninucleated?
Uni
Cardiac muscle: multi or uninucleated?
Uni (sometimes bi)
Describe muscle contraction? 12 steps
- Acetylcholine release at the neuromuscular junction
- Ach binds to sarcolemna = depolarization
- Depolarization spreads through T-tubules
- Ca2+ is released by the sarcoplasmic reticulum
- Ca2+ binds to troponin
- Shift in tropomyosin= exposure of myosin binding sites on actin
- Myosin binds to actin
- Myosin releases ADP + Pi = contraction
- Ach is degraded at synapse
- Ca2+ is resorbed by sarcolemna
- ATP binds to myosin= actin release
- ATP is hydrolyzed to ADP + Pi = recocking of myosin head
What is the relationship between the thymus and Ach?
Thymus has Ach receptors
What are the 5 cell types that do not undergo mitosis?
- Neurons
- Red and white blood cells
- All muscle cells (3 types)
Out of all of the endocrine system hormones, which ones are steroid hormones? 5
Glucocorticoids Aldosterone Estrogen Progesterone Testosterone
What happens in the proximal convoluted tubule of the nephron? 2
- Bulk resorption of glucose, aas, vitamins, salt, and water
- Absorption of HUNK: H+, urea, NH3, and K+
What happens in the descending limb of the loop of Henle of the nephron?
Water resorption
What happens in the ascending loop of Henle of the nephron? What about in the diluting segment?
Salt resorption
Loop is thicker in diluting segment (mito) and can give extra salt to blood: active transport
What happens in the distal convoluted tubule of the nephron? 2
- Salt resorption
2. Waste product (HUNK) absorption
What part of the nephron is responsive to aldosterone?
DCT and collecting duct
What part of the nephron is responsive to ADH?
Collecting duct
What happens in the collecting duct of the nephron? What does it control?
Water resoption; controls urine concentration
What is another name for coenzyme Q?
Ubiquinone