Ch. 3 Lab Flash Cards Cell Biology, Mitosis, and Molecular Genetics

Flashcards covering light microscopy, cell organelles, cell cycle and mitosis phases, cellular transport, and molecular genetics (transcription and translation).

What is the alternative name and magnification range for the eyepiece lens of a common light microscope?

It is also known as the ocular lens and serves as the first point of magnification, providing a $10\times$ or $15\times$ magnification.

What is the primary function of the nucleolus inside the cell nucleus?

The nucleolus is responsible for producing ribosomal RNA (rRNA) and assembling ribosomes.

What structural feature is found inside a mitochondrion, and what essential molecule does it produce?

It contains internal folded structures called cristae and is responsible for producing cellular energy in the form of ATP.

What are lysosomes, and what is their functional role within animal cells?

Lysosomes are membrane-bound vesicles filled with digestive enzymes that break down worn-out cell structures, foreign debris, and ingested substances.

What functions do peroxisomes perform in eukaryotic cells?

Peroxisomes contain peroxides and oxidase enzymes that detoxify harmful substances such as alcohol and formaldehyde, as well as break down free radicals into hydrogen peroxide and water.

What are the three sub-phases of interphase in the cell cycle and their respective primary events?

During the $G_1$ phase, the cell grows; during the $S$ phase (synthesis), the cell duplicates its DNA; and during the $G_2$ phase, the cell continues growing before entering mitosis.

What occurs when non-dividing cells exit the active cell cycle?

They enter a non-dividing state called the $G_0$ phase, typical for specialized cells like nerve and muscle cells.

What key structural changes occur inside the cell during prophase of mitosis?

Chromatin condenses into visible chromosomes, the mitotic spindle apparatus begins to assemble from centrosomes, and the nuclear envelope breaks down.

How can metaphase be uniquely identified during microscopic observation of cell division?

Chromosomes line up along a single straight axis in the center of the cell known as the metaphase plate.

What action occurs to sister chromatids during anaphase?

Centromeres split and individual sister chromatids are pulled apart toward opposite poles of the cell.

What key cellular events occur during telophase and cytokinesis in animal cells?

In telophase, nuclear envelopes reform around chromatin at each pole; in cytokinesis, a cleavage furrow pinches the cytoplasm to yield two distinct daughter cells.

What fundamental structural feature distinguishes prokaryotic cells from eukaryotic cells?

Eukaryotic cells contain a membrane-enclosed nucleus and membrane-bound organelles, whereas prokaryotic cells lack a nucleus and membrane-bound organelles.

Which four basic components are present in all living cells?

Genetic material (DNA), a plasma membrane, cytoplasm (cytosol), and ribosomes.

What two primary protein structures make up the cytoskeleton, and what type of support does each provide?

Microtubules (composed of tubulin) provide compressional support, while thin microfilaments provide tensional support.

How is the central dogma of molecular biology defined?

It describes the flow of genetic information from DNA to messenger RNA (mRNA) via transcription, and from mRNA to proteins via translation.

Which enzyme executes transcription, and where does this process occur in eukaryotic cells?

Transcription is carried out by RNA polymerase and takes place inside the nucleus.

What is the function of transfer RNA (tRNA) during protein translation at the ribosome?

tRNA transfers specific amino acids from the cytoplasm to the growing polypeptide chain by matching its anticodon to complementary mRNA codons.

What is the specific start codon in mRNA, and which amino acid does it encode?

The start codon is AUG, which codes for the amino acid methionine.

How are phospholipids arranged within the cell membrane according to the fluid mosaic model?

They form a double layer (bilayer) arranged tail-to-tail, where hydrophilic polar heads face the aqueous exterior/interior and hydrophobic fatty acid tails face inward away from water.

What is the primary operational difference between passive transport and active transport across the plasma membrane?

Passive transport moves substances down their concentration gradient without cellular energy input, whereas active transport uses energy in the form of ATP to move substances across the membrane.

What differentiates phagocytosis from pinocytosis?

Phagocytosis ("cell eating") involves engulfing large solid particles or bacteria using pseudopods, while pinocytosis ("cell drinking") non-selectively engulfs extracellular fluid containing dissolved solutes.