Bio Notes - AI Flashcards
What is biology?
A science that studies living organisms and their interactions.
What is biostatistics?
A group of procedures used by biologists to interpret data.
List the two types of biostatistics.
- Descriptive
- Inferential
What is the cell theory?
All organisms consist of cells, which are the smallest units of life.
What are the properties of life shared by all organisms?
- Made of cells
- Capable of processing energy
- Metabolize
- Respond to environment
- Adapt to environment
- Can reproduce and pass on traits
What is the first law of thermodynamics?
Energy cannot be created or destroyed; it can only be converted from one form to another.
What is the second law of thermodynamics?
The total amount of entropy tends to increase in the Universe.
What do cells need to counteract the tendency of increasing entropy?
Continual energy input from food or sunlight.
What are the two types of cells?
- Prokaryotes
- Eukaryotes
What is a virus?
Considered non-living because they cannot reproduce without a host cell.
What are the main macromolecules found in cells?
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
Define metabolism.
The sum total of the chemical reactions that occur in the cell.
What is anabolism?
The process where cells link monomers to form polymers by dehydration synthesis.
What is catabolism?
The process where macromolecules are broken down into their component monomers by hydrolysis.
What is the general composition of carbohydrates?
CHO (Carbon, Hydrogen, Oxygen)
What are monosaccharides?
Single sugar molecules, typically represented as (CH2O)n.
What are the two types of nucleic acids?
- DNA (Deoxyribonucleic acid)
- RNA (Ribonucleic acid)
What is the function of ATP?
Acts as an energy carrier in metabolism.
Fill in the blank: The plasma membrane is _______ to hydrophilic substances.
impermeable
What is the role of the endomembrane system?
To produce, fold, modify, sort, and transport proteins.
What is the structure of the nucleus?
Enveloped by a double membrane called the nuclear envelope.
What is the function of lysosomes?
Contain hydrolytic enzymes for digestion within the cell.
What is the primary function of mitochondria?
Cellular respiration and production of ATP.
What are microtubules made of?
Tubulin protein dimers.
True or False: Prokaryotic cells have membrane-bound organelles.
False
What is the composition of the cytoskeleton?
Made of proteins that maintain cell shape and anchor organelles.
What do saturated fatty acids contain?
No double bonds between carbon atoms.
What role do ribosomes play in the cell?
Site of protein synthesis.
What is the purpose of the Golgi apparatus?
Completes protein folding and modifies proteins.
What is a major characteristic of eukaryotic cells?
Contain membrane-bound organelles.
Fill in the blank: The _______ maintains the cell as a distinct, separate entity.
plasma membrane
What is the primary structure of proteins?
Linear sequence of amino acids.
What is the function of chloroplasts?
Photosynthesis.
What is the function of the central vacuole in plant cells?
Storage of wastes, ions, and water homeostasis.
What are the properties of membranes?
- Flexible
- Self-sealing
- Fluid
Membranes can take various shapes, interact to form enclosed environments, and exhibit fluidity influenced by temperature and cholesterol.
What is the Fluid Mosaic Model?
It describes the lateral movement of phospholipids and membrane proteins embedded within the membrane.
Integral membrane proteins have hydrophobic sections that interact with the hydrophobic core of the phospholipid bilayer.
What is selective permeability in membranes?
Membranes are permeable to hydrophobic/non-polar molecules and impermeable to hydrophilic/polar molecules and large macromolecules.
This property helps cells maintain homeostasis.
What types of transport do membrane-associated proteins facilitate?
- Passive transport (channels, transporters, pores)
- Active transport (pumps)
- Enzymatic functions
- Receptors and signal transduction
Transport includes various mechanisms for moving substances across the membrane.
What is passive transport?
Movement of molecules down their concentration gradients without energy input.
Examples include osmosis, diffusion of lipid-soluble molecules, and facilitated diffusion.
What is active transport?
Movement of solutes against their gradients, requiring energy (ATP).
Examples include Na+/K+ ATPase pump and H+/ATPase pump.
What is the function of the Na+/K+ pump?
It maintains the electrochemical gradient across the plasma membrane of animal cells.
This pump exchanges sodium ions for potassium ions.
What are the phases of the cell cycle?
- G0: Quiescence
- G1: Gap phase 1
- S: Synthesis
- G2: Gap phase 2
- M: Mitosis
G1, S, and G2 phases form the interphase.
What occurs during prophase of mitosis?
Chromosomes condense, nucleolus disappears, and nuclear envelope breaks down.
Chromosomes appear X-shaped; centrosomes move to opposite poles.
What is apoptosis?
A genetically controlled process leading to programmed cell death.
It involves the activation of caspases, chromatin condensation, and formation of apoptotic bodies.
What are the advantages of sexual reproduction?
- Increases genetic variability
- Enhances survival potential in changing environments
Variation arises from meiosis, fertilization, and development.
What is the role of crossing over during meiosis?
It allows exchange of genetic material between homologous chromosomes, increasing genetic diversity.
This occurs during prophase I.
What does independent assortment mean in meiosis?
It refers to the random distribution of maternal and paternal chromosomes into gametes.
This occurs during metaphase I.
What is semi-conservative DNA replication?
Each new DNA molecule consists of one old strand and one new strand.
This ensures that genetic information is accurately passed on.
What is the replication fork?
The Y-shaped structure where DNA synthesis occurs.
It involves the simultaneous synthesis of complementary daughter strands.
Fill in the blank: The human diploid number is _______.
46
This includes 23 pairs of chromosomes.
True or False: Mitosis results in four haploid cells.
False
Mitosis produces two identical diploid daughter cells.
What is the function of aquaporins?
They facilitate the movement of water across cell membranes.
This process is known as facilitated osmosis.
What is the replication fork?
Y shaped structure where synthesis of 2 complementary daughter strands occurs simultaneously
The synthesis occurs in the 5’ → 3’ direction for both strands.
What is required to initiate DNA synthesis?
Primer
Primer provides the initial 3’OH, which is essential for DNA replication.
What are Okazaki fragments?
Many short DNA segments formed on the lagging strand
These fragments are 1000-2000nt in E. coli and 100-200nt in eukaryotes.
What type of replication is DNA replication?
Semi conservative
Each new DNA molecule consists of one old strand and one new strand.
What enzyme is responsible for melting or unzipping the parental strands during DNA replication?
Helicase
Helicase unwinds the DNA double helix.
What is the role of DNA topoisomerase during DNA replication?
Reduces strain (supercoiling) produced by unwinding the parental strands
It acts ahead of the replication forks by cutting the DNA strands.
What keeps the parental strands apart during DNA replication?
Single-strand binding proteins
These proteins prevent the strands from reannealing.
In what direction is DNA synthesized?
5’ to 3’ direction
DNA polymerase synthesizes DNA in this direction.
What happens to RNA primers after DNA synthesis?
They are degraded and replaced by DNA
This step is catalyzed by DNA polymerase I.
What is the problem associated with linear chromosomes during replication?
Overhang of ssDNA
The last primer removal cannot be filled in, leading to chromosome shortening.
What enzyme solves the problem of telomere shortening?
Telomerase
Telomerase adds telomeres to chromosomes during development.
What are telomeres?
Sequences at both ends of linear chromosomes consisting of hexanucleotide repeats (AGGGTT)
They protect the coding region from being lost with each round of DNA replication.
What is the Hayflick limit?
Cells stop dividing as chromosomes reach a critical shorter length
This limit is associated with telomere shortening.
True or False: Cancer cells typically have low levels of telomerase activity.
False
Cancer cells have high levels of telomerase activity, preventing telomere shortening.
What role do telomeres play in somatic cells?
Protect coding regions from being lost
If telomere length is not maintained, cells can divide about 50 times before losing genetic information.
