Cell Structure and Cell Cycle Flashcards

Comprehensive vocabulary flashcards covering cellular biology and cell division phases as presented in the lecture transcript.

Prokaryotic Cells

Cells where the nucleus is not enclosed within a membrane, DNA is located in the nucleoid region, and no membrane-bound organelles are present.

Eukaryotic Cells

Cells with a membrane-bound nucleus containing DNA, found in plants, animals, fungi, and protists.

Cellulose

Molecules in plant cell walls that crystallize into strong microfibrils and grow end to end through the addition of glucose molecules.

Hemicellulose

The substance that holds cellulose microfibrils together in the plant cell wall.

Protoplasm

The component of the cell composed of all organelles, proteins, lipids, nucleic acids, and water.

Central Dogma

The flow of genetic information characterized by the sequence: $DNA \rightarrow RNA \rightarrow Protein$.

Nucleolus (Nucleoli)

The site within the nucleus where ribosomes are synthesized and partially assembled, occupying approximately $50\%$ of the nucleus.

Tonoplast

The membrane surrounding the central vacuole in a plant cell.

Matrix

The interior fluid-filled space of the mitochondrion.

Chromoplast

A plastid containing yellow, orange, or red carotenoid pigments that give color to fruits, flowers, and some roots.

Leucoplast

A colorless plastid mainly responsible for the storage of nutrients like starch, oils, and proteins.

Amyloplast

A specific type of leucoplast that stores starch and is commonly found in roots, tubers, and seeds.

Phytoferritin

An iron-storage protein in plants, located mostly in the leaves.

Polysome

A cluster of ribosomes bound to a single $mRNA$ strand working simultaneously to make multiple copies of the same protein.

70S Ribosome

The ribosome type found in prokaryotes, composed of a $30S$ small subunit and a $50S$ large subunit.

80S Ribosome

The ribosome type found in eukaryotes, composed of a $40S$ small subunit and a $60S$ large subunit.

Rough Endoplasmic Reticulum (RER)

A network of membrane-bound tubes with ribosomes attached to its surface, responsible for protein synthesis and transport.

Dictyosomes

Organelles that modify, package, and transport products from the ER; collectively referred to as the Golgi Apparatus in animal cells.

Peroxisomes

Small membrane-bound organelles that participate in the digestion of ethanol in animal cells and play a role in photorespiration in leaf cells.

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes, often called 'suicide bags' of the cell.

Apoptosis

The process of programmed cell death.

Microtubule Organizing Centers (MTOCs)

Structures in plant cells that perform the function of organizing microtubules, serving as an alternative to centrioles.

Microtubules

Hollow protein tubes approximately $25\,nm$ in diameter made of tubulin dimers ($\alpha$-tubulin and $\beta$-tubulin).

Plasmodesmata

Fine channels approximately $40\,nm$ in diameter that connect adjacent plant cells for direct transport and communication.

Apoplast

The system consisting of intercellular spaces and cell walls that allows the diffusion of gases and water outside the plasma membrane.

Chitin

The material that makes up the cell walls of fungal cells instead of cellulose.

Cell Cycle Arrest

A state where cells permanently leave the cell cycle and remain in a $G_1$-like state.

Endoreduplication

A process where $DNA$ replicates repeatedly without cell division, producing giant nuclei with thousands of gene copies.

Gene Amplification

A process where only selected genes are replicated multiple times to increase the production of specific proteins.

Histones

Proteins that bind to $DNA$ to provide structure and protection while organizing it into chromosomes.

Separase

An enzyme that digests cohesin during metaphase to prepare sister chromatids for separation.

Phragmoplast

A structure that forms at the center of a plant cell during cytokinesis to guide the fusion of vesicles into a cell plate.

Arithmetic Growth

A growth pattern where only one daughter cell continues dividing while the other differentiates.

Geometric Growth

A growth pattern where both daughter cells continue dividing, resulting in exponential growth.

Synapsis

The pairing of homologous chromosomes during the Zygotene substage of Prophase I.

Pachytene

The substage of Prophase I in Meiosis where crossing-over occurs and $DNA$ recombines between homologous chromosomes.

Chiasmata

X-shaped structures representing the sites where crossing-over has occurred, which remain visible during the Diplotene stage.