38 Questions
What is the range of carbon atoms in monosaccharides?
3 to 6
What is the general formula of monosaccharides?
CnH2nOn
What is unique about the arrangement of carbon atoms in monosaccharides?
Unbranched arrangement
How many different monosaccharide types occur naturally?
More than 200
What is characteristic of polymers of monosaccharides?
Low diversity
What is the monosaccharide type that makes up glycogen and starch?
α-D-glucose
What is the monosaccharide type that makes up cellulose?
β-D-glucose
What is a characteristic of monosaccharides in forming polymers?
They rarely combine with one another
What is the characteristic feature of monosaccharides?
Unbranched carbon chain with several hydroxyl groups
What is the main difference between aldoses and ketoses?
Type of reducing function (aldehyde or ketone)
What is the simplest type of monosaccharide, based on the number of carbon atoms?
Triose
What is the result of an intramolecular reaction between the hydroxyl group and the carbon of the aldehyde or ketone group?
Formation of a cyclic molecule
Why are cyclic monosaccharides more stable than linear ones?
They have lower free energy
What is the name of the cyclic monosaccharides with six-member rings?
Pyranoses
What is the name of the cyclic monosaccharides with five-member rings?
Furanoses
How can monosaccharides be classified based on their cyclic structure?
Based on the type of cycle (pentagonal or hexagonal)
What is the binding site for amino acids in tRNA?
3'OH end
What is the function of aminoacyl-tRNA synthetases?
To recognize and charge tRNA with corresponding amino acids
What is the characteristic of the secondary structure of tRNA?
It is a trefoil structure
What is the role of snRNA in the cell?
To mature and splice RNA
What is the length of snRNA?
Between 50-200 nucleotides
What is the name of the complex formed by snRNA and specific proteins?
Small nuclear ribonucleoprotein
What is the primary role of helicases and gyrases or topoisomerases in transcription?
To unwind the DNA double helix
What is the main difference between transcription and replication in terms of template usage?
Replication uses both DNA strands as templates, while transcription uses one strand
What is the typical sequence of events during transcription?
Initiation, elongation, termination
What is the primary function of RNA polymerase during transcription?
To synthesize RNA molecules using DNA as a template
What is the purpose of the specific sequences that represent gene start and end?
To initiate and terminate transcription
What is the primary difference between mRNAs and rRNAs?
mRNAs are involved in gene expression, while rRNAs are involved in protein synthesis
How many RNA types are described in the provided content?
4
What is the total number of genes in human cells, according to the content?
30,000
What is the primary mechanism by which DNA exerts its activity?
By encoding proteins that perform specific functions
What is the role of proteins in determining the molecular identity of cells?
They are responsible for the molecular identity of cells through the HLA system and blood groups
What is the primary function of proteins in gene expression?
To interact with specific DNA/RNA sequences
What is the role of proteins in the morphology of organisms?
They determine the size and shape of organisms
What is the result of proteins interacting with one another and with diverse molecules?
They achieve their functions
What is the role of proteins in the storage and transportation of particles?
They are involved in the storage and transportation of a variety of particles
What is the relationship between proteins and the life of cells and organisms?
Proteins perform almost all functions that sustain life of cells and organisms
What is the role of proteins in the physiological processes of gene expression?
They are involved in the complex processes of gene expression
Study Notes
Proteins and their Functions
- Proteins are responsible for almost all functions that sustain life of cells and organisms
- They determine cell structure, shape, and perform nearly all physiological functions
- Proteins determine the molecular identity of cells and are responsible for morphology of organisms (e.g. skin and hair colors, size, and shape)
- They are involved in crucial physiological processes such as gene expression, DNA replication, and transportation of particles
- Proteins achieve their functions by interacting with one another and with diverse molecules from other classes (organic and inorganic)
Carbohydrates
- Carbohydrates are classified based on the number of carbon atoms per molecule, type of functional group, cyclic shape, and number of monomers
- Monosaccharides (simple carbohydrates) have the general formula CnH2nOn, where "n" ranges between 3 and 6
- Aldoses have an aldehyde group, while ketoses have a ketone group
- Glyceraldehyde and dihydroxyacetone are the simplest monosaccharides, named trioses since each comprises 3 carbon atoms
- Monosaccharides can occur in open-chain or cyclic (ringed) molecules, with the cyclic form being more stable
Transcription and Translation
- Transcription of genes into RNA is carried out by specific enzymes named RNA polymerases, helped by helicases and gyrases or topoisomerases
- Transcription principle is similar to that of replication, using DNA as a template to determine the sequence of the newly synthesized RNA molecule
- Unlike DNA replication, transcription is concerned with specific DNA stretches, named genes
- Transcription occurs in three steps: initiation, elongation, and termination
RNA Types
- RNA is divided into several classes: rRNA (ribosomal), mRNA (messenger), tRNA (transfer), snRNA (small nuclear), and others
- Each tRNA is characterized by an anticodon and is specifically charged with the corresponding amino acid
- All tRNA types have the same general trefoil structure with three loops, packed into an L-shaped tertiary structure
- snRNA length is between 50-200 nucleotides and are always associated with specific proteins forming nucleoprotein complexes (snRNP)
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