Cell Structure
What is the smallest unit of structure and function in all living things?
What is a cell?
What macronutrient is made of amino acids?
Protein
What molecule stores genetic information?
DNA
[True/False] Epigenetic changes are permanent and passed down to offspring.
False
What is contact inhibition and why is it important?
It stops cells from growing when they touch other cells. This keeps tissues from getting too crowded
This structure is made of phospholipids and controls what enters and exits the cell.
What is the plasma (cell) membrane?
What are ionic, covalent, metallic, and hydrogen bonds?
Ionic bonds are a transfer of electrons
Covalent bonds are a sharing of electrons
Hydrogen bonds are a weaker type of bond between a hydrogen atom and another HIGHLY electronegative atom - can be within the same molecule or BETWEEN two molecules.
What is the name of the process that converts
DNA -> RNA?
Transcription
What are the steps of enzyme action in the correct order?
1. Substrate Binds
2. Enzyme Changes Shape
3. Products Released
What is the difference between proto-oncogenes and oncogenes?
Proto-oncogenes: normal genes that help cells grow
Oncogenes: mutated or overactive versions of proto-oncogenes
Why are glycoproteins important for immune system recognition?
They help cells identify and respond to foreign invaders.
How does a mutation that changes one amino acid affect protein function?
It can change the shape or folding of the protein, which may stop it from working properly.
RNA polymerase doesn’t need a primer—why not?
It can start making RNA on its own by binding directly to the DNA
How do changes like DNA methylation affect gene expression?
They can turn genes off or on without changing the DNA code.
[case] A patient has a BRCA1 mutation. How does this relate to breast cancer risk?
BRCA1 helps repair DNA.
A mutation increases the chance of cancer because damaged DNA builds up.
In a phospholipid bilayer, describe the direction of the hydrophilic and hydrophobic regions and why it matters.
Hydrophilic heads face out, hydrophobic tails face in, forming a stable barrier.
How does the amphipathic nature of phospholipids lead to membrane formation?
They form a bilayer because:
- The water-loving heads face water
- The water-hating tails face each other
What are two methods of transcriptional regulation and what do they do?
Transcription Factors - proteins that bind to specific DNA sequences to either promote or inhibit RNA polymerase binding (activators and repressor).
Histone modifications: (like acetylation or methylation) can alter how tightly DNA is wound around histones, making it more or less accessible to the transcription machinery.
1.) What do these processes do to histones/DNA exposure: histone acetylation and DNA methylation.
2.) Complete the sentence:
1.) Acetylation generally promotes gene expression by making DNA more accessible, while methylation typically silences genes by making DNA less accessible.
2.) acetyl, lysine
methyl, cytosine
Briefly describe the key steps involved in the metastatic cascade, from invasion to colonization.
Why do certain medications or nutrients need to be specially designed to cross the cell membrane, and what properties allow them to pass through more easily?
The cell membrane is selectively permeable.
Only small, nonpolar, or lipid-soluble molecules can pass through easily.
Large or charged molecules need transport proteins or must be modified (like being packaged in liposomes) to enter the cell.
[Scenario] A cell is exposed to heat, denaturing a protein. What bonds break first, and what happens to its function?
- Hydrogen Bond
- The protein loses its specific 3D shape
1.) Explain the Central Dogma of Biology.
2.) Explain what "the genetic code is redundant" means (how many codons are there vs. how many amino acids are there). Why is this beneficial?
1.) Information flows from DNA to RNA to protein. DNA is transcribed into RNA, and then RNA is translated into protein.
2.) Multiple Codons in mRNA can code for the same amino acid (64 codons - 20 amino acids). Beneficial because it can buffer against the effects of mutations, allowing for some flexibility in the genetic sequence without altering the protein being produced.
Describe competitive inhibition, noncompetitive inhibition (use the term "allosteric"), and uncompetitive inhibition.
Competitive inhibition – The substrate and the inhibitor are both able to bind to the active site and they compete with one another.
Noncompetitive inhibition – The inhibitor does not bind at the active site, but at an allosteric site.
Uncompetitive inhibition – The inhibitor only sticks to the enzyme after the substrate is already bound. Once it latches on, the enzyme–substrate pair can’t make the product.
[case] A cell skips all checkpoints. What happens, and which genes might be involved?
It may become cancerous.
Some affected genes: p53 or BRCA1