Medical Biology: chapter 1

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Questions and Answers

What role do sugars play in the formation of polysaccharides?

They act as coenzymes.

They serve as monomers. (correct)

They perform lipid synthesis.

They function as amino acids.

Which structure is not a recognized level of protein structure?

Nucleic structure (correct)

Primary structure

Tertiary structure

Quaternary structure

How many possible different protein sequences could a typical protein of about 400 amino acids long potentially have?

20,400 (correct)

40,800

64,000

2,048,000

What is the primary function of proteins within a cell?

To catalyze chemical reactions Signup and view all the answers

During cell division, where is most of the DNA located in eukaryotic cells?

In the nucleus Signup and view all the answers

What do nucleic acids primarily carry out in a cell?

Carry coded information for making proteins Signup and view all the answers

What is the primary structural component of the prokaryotic cell wall?

Peptidoglycan Signup and view all the answers

Which type of DNA molecule is present in prokaryotic cells besides chromosomal DNA?

Plasmids Signup and view all the answers

Which statement best describes the role of polynucleotides in biological systems?

Polynucleotides can replicate themselves and direct the synthesis of other molecules. Signup and view all the answers

What adaptation allows prokaryotic cells to thrive in extreme environments?

Small size Signup and view all the answers

What is the significance of nucleotide pairing in polynucleotides?

It allows for one polynucleotide to template the synthesis of another. Signup and view all the answers

Which of the following best characterizes the structure of present-day proteins?

They consist of a defined sequence of 20 different amino acids. Signup and view all the answers

Which structure of prokaryotic cells is responsible for movement?

Flagella Signup and view all the answers

Which component of the cell envelope is composed of lipopolysaccharides?

Outer Membrane Signup and view all the answers

How do specialized RNA molecules contribute to biochemical reactions?

They can catalyze specific biochemical reactions. Signup and view all the answers

What is the average diametric size range of bacterial cells?

0.1–5.0 µm Signup and view all the answers

What is the role of phospholipids in the formation of cell membranes?

They are the fundamental building blocks of all cell membranes. Signup and view all the answers

What is the function of periplasm in prokaryotic cells?

Contain proteins for nutrient breakdown Signup and view all the answers

What was likely a pivotal step in the evolution of early cellular life?

Formation of self-replicating RNA molecules. Signup and view all the answers

What distinguishes RNA's role compared to DNA in present-day cells?

RNA acts as a mediator in protein synthesis, while DNA is the genetic repository. Signup and view all the answers

How do prokaryotic cells compare to eukaryotic cells in size?

They are about ten times smaller Signup and view all the answers

Which of the following organisms is often classified as a prokaryote?

E. coli Signup and view all the answers

How does the distinctive shape of RNA molecules impact their function?

It enables them to catalyze reactions and interact with other biomolecules. Signup and view all the answers

Which characteristic is NOT typical of prokaryotic cells?

Membrane-bound organelles Signup and view all the answers

Which of the following statements about cell membranes is accurate?

Cell membranes are essential for defining cellular boundaries and consist primarily of phospholipids. Signup and view all the answers

What term describes cells with the capability to give rise to an entire organism?

Embryonic stem cells Signup and view all the answers

Which of the following accurately describes the hierarchy of biological organization from simplest to most complex?

Atoms, Simple Molecules, Chain Molecules, Cells, Organs, Organisms Signup and view all the answers

Which statement about the zygote is true?

It is the first stage of complex organism development. Signup and view all the answers

What is the average diameter range of cells in a living organism?

1 micrometer to hundreds of micrometers Signup and view all the answers

Which level of organization includes everything in the levels below it?

Ecosystems Signup and view all the answers

Which of the following statements about reductionism is incorrect?

It applies only to physical sciences, not biology. Signup and view all the answers

What defines the internal mechanisms that determine the kind of organism developed from a zygote?

The genetic information within the cell Signup and view all the answers

What best describes the largest structure in biological terms?

An organism Signup and view all the answers

Which of the following correctly distinguishes somatic cells from embryonic stem cells?

Somatic cells are specialized and cannot develop into an organism. Signup and view all the answers

Which molecule is primarily involved in the genetic instructions of a cell?

DNA Signup and view all the answers

Which organisms are classified as primary energy converters in ecosystems?

Producers Signup and view all the answers

What distinguishes inorganotrophic organisms from organotrophic organisms?

Inorganotrophs primarily feed on sunlight or inorganic compounds. Signup and view all the answers

Which of the following is an example of a chemoautotrophic organism?

Bacteria found in extreme environments Signup and view all the answers

How do decomposers contribute to nutrient cycling in an ecosystem?

By breaking down dead organic matter. Signup and view all the answers

Which of the following organisms can be classified as photoautotrophs?

Algae Signup and view all the answers

Which statement accurately describes heterotrophs?

They obtain energy by consuming other organisms. Signup and view all the answers

What is the main source of free energy for living organisms in ecosystems?

Sunlight or chemical compounds Signup and view all the answers

Which is a characteristic of organotrophic organisms?

They obtain energy by consuming organic compounds. Signup and view all the answers

Which type of organisms are primarily responsible for decomposing wood?

Fungi Signup and view all the answers

What type of autotroph primarily utilizes sunlight for energy?

Photoautotrophs Signup and view all the answers

Study Notes

Polynucleotides

Polynucleotides are random in length and sequence.
They can act as a template for the synthesis of another polynucleotide.
They are made of nucleotide pairs: G with C and U with A
Polynucleotides can direct their own synthesis.

Self-replicating Molecules

RNA molecules can adopt a distinctive shape due to nucleotide pairing.

Evolution of Cells

RNA molecules can catalyze biochemical reactions.
DNA is the repository of genetic information, RNA acts as a go-between to direct protein synthesis.

First Cells

Membranes were critical for forming the first cells.
Phospholipids create the fundamental building blocks of all cell membranes.
Membranes define the first cell.

Prokaryotic Cells

Prokaryotic cells are significantly smaller than eukaryotic cells, meaning they can grow faster and multiply more rapidly.
They come in many shapes and sizes.
Bacteria are the most numerous prokaryotes.
Cyanobacteria can be single-celled or filamentous chains of cells.
Prokaryotic cells have been found 7 miles deep in the ocean and 40 miles up in the atmosphere.

Prokaryotic Cell Structure

Appendages: Pili, Flagella, Axial Filaments
Cell Envelope: Glycocalyx (Capsule), Outer Membrane, Cell Wall, Periplasm, Plasma or Cell Membrane

The Human Body

Begins as a single cell (zygote).
Has about 60-100 trillion cells.
Contains about 200 different types of cells.
Embryonic stem cells give rise to the entire body.

Comparative Sizes and Levels

Cells can vary between 1 micrometer and hundreds of micrometers in diameter.
Reductionism helps understand complex systems by studying their parts: atoms, molecules, chain molecules, molecular structures, cells, organs, organisms, populations, communities, ecosystems.
Each level encompasses all lower levels.

Energy Flow in an Ecosystem

Ecosystems require a constant supply of energy from sunlight or chemicals.
Producers (Autotrophs) use sunlight or chemicals to make food.
- Photoautotrophs use sunlight: plants, algae, some bacteria.
- Chemoautotrophs use chemicals: microbes found in various inhospitable environments.
Consumers (Heterotrophs) get energy by eating food.
- Herbivores: eat plants.
- Carnivores: eat animals.
- Omnivores: eat both plants and animals.
Decomposers get energy by decomposing dead organisms.
- Fungi are the only organisms that decompose wood.

Monomers and Biopolymers

Cells produce three types of large polymers: polysaccharides, proteins, and nucleic acids.
Covalent and noncovalent interactions stabilize the molecules.

Proteins

Proteins vary greatly in size, shape, and function.
They enable different functions: small size hormones transmit signals, ion channels control ion concentration, and enzymes catalyze chemical reactions.
Proteins commonly range in length from 100 to 1000 amino acids.
If a protein is about 400 amino acids long, there are 20400 possible different protein sequences.

Nucleic Acids

Nucleic acids carry coded information for making proteins.

Genome and Chromosomes

The genome is packaged into chromosomes.
Each chromosome contains a single linear DNA molecule associated with certain proteins.
The genome of an organism comprises its entire complement of DNA.

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Description

Explore the fundamental concepts of polynucleotides, the evolution of cells, and the characteristics of prokaryotic cells in this informative quiz. Delve into the roles of RNA and DNA in biological processes and understand the significance of cell membranes in the formation of life.