Biology Exam 2

Cholesterol molecules are capable of interacting with the plasma membrane of cells. Where would a cholesterol molecule most likely be found when it interacts with the plasma membrane of a cell?

Interacting with fatty acid tails in the interior of the plasma membrane, away from the watery intra/extracellular environment

Lipids are important for many cellular functions in our bodies. Like many nutrients, lipids are transported around our bodies via the bloodstream.  Unlike many nutrients, lipids require specialized structures called lipoproteins to remain soluble in blood until delivered to target cells. Based on the composition of blood, predict the properties of the outer surface and interior of a lipoprotein that would enable lipid transport through the bloodstream.

Outer surface = hydrophilic; Interior = hydrophobic

A researcher working with an isolated set of cells that have all the same characteristics. Part of growing and raising the cells is ensuring they’re in the proper environment with the appropriate nutrients and solution around them. The researcher recently brought in a new graduate student who was placed in charge of raising and caring for these cell lines. One day, the researcher is working with the cell lines and, after examining them under a microscope, discovers that all the cells have either become overly swollen or completely burst, ruining the study. Given this information, what type of solution did the graduate student likely administer to the cells to produce this result?

Hypotonic saline

Why do cells burst and become swollen in hypotonic saline

Water rushes into the cell through osmosis to balance the higher concentration of solutes inside the cell compared to the outside. Example: Lower concentration of solute and higher concentration of water

How do you determine whether a molecule is able to move across the membrane via simple diffusion?

Size: small molecules pass easily, Polarity: nonpolar pass easily, Lipid Solubility: High lipid solubility means it dissolves in fats so it can pass the lipid layer

How do you determine a passive transport?

Molecules move across a cell membrane from a high concentration to a low concentration without using cellular energy

Why would a cell need a protein transporter embedded in its cell membrane?

To move specific polar molecules, ions, and large nutrients to move through the hydrophobic lipid bilayer

How do you determine whether an ion is being moved against their concentration gradient?

They travel from an area of low concentration to an area of high concentration. It does require cellular energy so active transport

Ribosome

Cellular machines that synthesize proteins by reading messenger RNA (mRNA) and translating the genetic code into amino acid sequences.

Nucleus

The structure in a cell that contains the DNA and chromosomes. This organelle has a membrane around it and is where RNA is made from the DNA in the chromosomes.

Golgi Apparatus

A cell organelle that modifies, sorts, and packages proteins and lipids for transport to different locations in the cell or outside the cell.

Plasma Membrane

Semipermeable membrane that separates the inside of a cell from its outside environment.

Endoplasmic Reticulum

A cell organelle that is a network of tubes and sacs that extends throughout the cytoplasm of a cell. It is a large, dynamic structure that serves many roles in the cell, including calcium storage, protein synthesis, and lipid metabolism.

Lysosome

A membrane-bound organelle found in animal cells that acts as the cell's "waste disposal system" by containing digestive enzymes which break down worn-out cell parts, cellular debris, and ingested materials from outside the cell.

Mitochondria

Small organelles found within the cells of most eukaryotes, responsible for producing the majority of the cell's chemical energy in the form of adenosine triphosphate (ATP), often referred to as the "powerhouse of the cell" due to their primary function in energy generation; they have a double membrane structure and contain their own DNA, inherited solely from the mother.

Cytoplasm

The gelatinous liquid that fills the inside of a cell. It is composed of water, salts, and various organic molecules.

Microtubules

Hollow, tube-shaped structures that are a major component of the cytoskeleton in eukaryotic cells.

Prokaryote

Any organism that lacks a distinct nucleus and membrane-bound organelles due to the absence of internal membranes. Bacteria are among the best-known of these organisms.

Eukaryote

An organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. These organisms include animals, plants, fungi, and protists.

Organelle

A subcellular structure that has one or more specific jobs to perform in the cell. Some organelles are separated from the cytoplasm by their own membrane, while others are not.

Endosymbiotic Theory

A hypothesis that explains how certain organelles in eukaryotic cells, particularly mitochondria and chloroplasts, originated from free-living prokaryotes, or bacteria. The theory suggests that these prokaryotes became organelles through a symbiotic relationship with another cell, where they survived instead of being digested or killed. Over time, the organelle and the host cell evolved together.

Cell Theory

The principle that suggests that all living things are made of cells, the cell is the basic unit of structure and organization in organisms, and all cells come from pre-existing cells.

Passive Transport

The diffusion of molecules with the concentration gradient, that is, from high to low concentration, in order to maintain equilibrium in the cells. The rate of diffusion for different substances is affected by membrane permeability.

Diffusion

The movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. The difference in the concentrations of the molecules in the two areas is called the concentration gradient. This process will continue until this gradient has been eliminated.

Osmosis

The process by which water molecules move through a semipermeable membrane from a region of higher water concentration to a region of lower water concentration.

Facilitated Diffusion

A passive transport process that allows molecules and ions to move across a cell membrane with the help of proteins. Often these proteins make up a channel that allows diffusion between inside and outside of the membrane.

Active Transport

The movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. This process requires cellular energy to achieve this movement.

What do Plant cells have that Animal Cells do not?

Plant cells have Chloroplast and Cell Wall

Where does protein synthesis occur?

In ribosomes

What cell organelles result from endosymbiosis

Chloroplast and Mitochondria

Mitosis

The process by which a parent cell divides into two daughter cells, each with a complete and identical set of chromosomes from the parent cell. This occurs in diploid body cells.

Diploid

The presence of two complete sets of chromosomes in an organism's cells, with each parent contributing a chromosome to each pair.

Meiosis

A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of sex cells (gametes).

Haploid

Refers to the presence of a single set of chromosomes in an organism's cells.

M Phase

The stage of the cell cycle when a cell divides.

Interphase

The stage in a cell cycle where a cell grows, replicates its DNA, and prepares for cell division.

G1 Phase

The first phase of the cell cycle in eukaryotic cell division. It's a growth phase that occurs during interphase, when the cell grows and replicates DNA.

G2 Phase

A stage in the cell cycle that occurs between the completion of DNA synthesis and the start of mitosis. It is the third subphase of interphase and is preceded by the S phase, when the cell's DNA is replicated.

S Phase

The period in the cell cycle when DNA replication occurs.

Cytokinesis

The final stage of cell division where the cytoplasm of a single cell physically splits into two separate daughter cells.

G0 Phase

Also known as the resting phase or gap phase, is a cell cycle phase where cells are not dividing or preparing to divide.

Karyotype

A visual representation of an individual's complete set of chromosomes, including their size, number, and shape.

Signaling Cell

The cell that releases a chemical message to other cells.

Signaling Molecule

A chemical message (such as a hormone or other similar compound).

Receptor Protein

A protein complex (often embedded in membranes) that binds to incoming chemical signals.

Responding cell

The focal cell that is targeted to receive a message and responds through signal transduction.

Signal Transduction

The process by which cells receive and respond to signals from outside the cell. It's a series of molecular events that transmit signals through a cell, often in response to chemical substances like hormones, neurotransmitters, and growth factors.

Endocrine Signal

Chemical signals, or hormones, that are released by glands and carried through the bloodstream to target cells in other parts of the body.

Which component of a phospholipid is found in the interior of a lipid bilayer?

Fatty Acids

What form of cell communication is blood clotting?

Paracrine

Proto-Oncogene

genes that code for positive cell cycle regulators; ensure cell cycle is happening

Normal Protein Function

Proto-ocogene

Tumor Suppressor Genes

code for negative regulator proteins; roadblock cell cycle and slow down cell cycle

Faulty Protein Function

Oncogene

Autocrine

Cell targets itself

Gap Junction

Cell targets cells by gap junctions

Paracrine

Cell targets nearby cells

Endocrine

Cell targets distant cell via bloodstream

What do phosphates do?

They activate things and charge things up