Chapter 3 BOOK NOTES PART 4

Cilia

Whiplike, motile cellular extensions that move substances across cell surfaces in one direction.

Flagella

Projections formed by microtubules, longer than cilia, used for cell propulsion.

Basal Bodies

Centrioles forming the bases of cilia and flagella, differing slightly in microtubule arrangement from the cilium or flagellum itself.

Microvilli

Tiny, fingerlike extensions of the plasma membrane that increase surface area, commonly found on absorptive cells.

Nucleus

Control center of the cell containing genetic instructions for protein synthesis and regulating protein production.

Nuclear Envelope

Double membrane barrier surrounding the nucleus, with outer membrane continuous with rough ER and inner membrane lined by nuclear lamina.

Nucleoli

Structures within the nucleus involved in ribosomal RNA synthesis and ribosome subunit assembly.

Chromatin

Complex of DNA and proteins within the nucleus, condensing to form chromosomes during cell division.

Nuclear Pore Complex

Protein complex regulating molecule entry and exit in the nucleus

Nucleoplasm

Jellylike fluid in the nucleus containing essential solutes

Nucleosomes

Basic units of chromatin with histone proteins and DNA

Histones

Proteins packaging and regulating DNA in chromatin

Extended Chromatin

Active chromatin segments regulating gene expression

Condensed Chromatin

Inactive chromatin segments visible under a microscope

Chromosomes

Highly condensed chromatin threads during cell division

Plasma Membrane

Phospholipid bilayer serving as an external cell barrier

Cytoplasm

Cellular region containing cytosol, organelles, and inclusions

Mitochondria

Double membrane-bound organelles for ATP synthesis

Ribosomes

Dense particles for protein synthesis, composed of RNA and protein

Rough Endoplasmic Reticulum

Membranous tubules studded with ribosomes for protein synthesis

Smooth Endoplasmic Reticulum

Membranous system devoid of ribosomes for lipid synthesis

Golgi Apparatus

Organelle processing and packaging proteins for transport

Golgi apparatus

Stack of flattened membranes and vesicles; packages, modifies, and segregates proteins.

Peroxisomes

Membranous sacs with detoxifying enzymes, including catalase.

Lysosomes

Membranous sacs with acid hydrolases for intracellular digestion.

Microtubules

Cylindrical structures supporting cell shape and movement.

Intermediate filaments

Stable cytoskeletal elements resisting mechanical forces.

Microfilaments

Fine filaments composed of actin for muscle contraction.

Centrioles

Paired bodies organizing microtubule network during cell division.

Inclusions

Cytoplasmic storage for nutrients, wastes, and cell products.

Flagellum

Long tail-like projection for cell propulsion.

Cell cycle

Series of changes from cell formation to reproduction, including interphase and mitotic phase.

Interphase

Period from cell formation to division, preparing for the next division.

G1 phase

Metabolically active phase with rapid protein synthesis and growth.

S phase

DNA replication phase ensuring identical genetic material for daughter cells.

G2 phase

Brief phase synthesizing proteins needed for division.

DNA replication

Process of replicating DNA before cell division for passing identical genetic material.

Mitotic phase

Cell division phase consisting of mitosis and cytokinesis.

Prophase

First phase of mitosis involving chromatin condensation and spindle formation.

Metaphase

Chromosomes aligning at the cell's equator in mitosis.

Anaphase

Chromatids separating and moving to opposite poles in mitosis.

Telophase

Final phase of mitosis with nuclear envelope reformation.

G1 checkpoint

Check for DNA damage and cell size before entering the S phase.

G2/M checkpoint

Ensures DNA replication and repair before cell division.

DNA Replication

Process of copying DNA strands to form two daughter molecules

Semiconservative Replication

Mechanism where each new DNA molecule contains one old and one new strand

Replication Fork

Point where DNA strands separate during replication

DNA Polymerase

Enzyme that positions complementary nucleotides during DNA replication

Sister Chromatids

Two identical copies of a chromosome connected at the centromere

Cell Division

Process of dividing a cell into two daughter cells

Mitosis

Nuclear division process resulting in two identical daughter nuclei

Cytokinesis

Division of the cytoplasm to form two daughter cells

Meiosis

Nuclear division process producing sex cells with half the genetic material

G1 Phase

First growth phase of interphase

S Phase

Synthesis phase of interphase where DNA is replicated

G2 Phase

Second growth phase of interphase before mitosis

Centromere

Region of a chromosome where sister chromatids are joined

Kinetochore

Protein structure at the centromere for microtubule attachment

Mitotic Spindle

Structure of microtubules that helps separate chromosomes during cell division

Cleavage Furrow

Indentation that forms during cytokinesis to divide the cell

Actin Filaments

Protein filaments forming the contractile ring during cytokinesis

DNA Ligase

Enzyme that splices DNA segments together during replication

Mitotic Phase

Phase of the cell cycle involving mitosis and cytokinesis

Cell Cycle

The series of events that take place in a cell leading to its division and duplication.

Contact Inhibition

The phenomenon where normal cells stop proliferating when they begin touching each other.

Gene

A segment of a DNA molecule that carries instructions for creating one polypeptide chain.

Genetic Code

The set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins.

Codons

A sequence of three nucleotides that together form a unit of genetic code in DNA or RNA.

Anticodons

A sequence of three nucleotides in a transfer RNA molecule that pairs with a complementary codon in mRNA.

Triplets

A sequence of three DNA or RNA nucleotides that stands for one amino acid.

Exons

Coding regions of genes that contain the information needed to produce proteins.

Introns

Intervening sequences in genes that do not code for proteins but have regulatory functions.

Messenger RNA (mRNA)

A type of RNA that carries the coded information from DNA to the cytoplasm for protein synthesis.

Ribosomal RNA (rRNA)

RNA that, along with proteins, forms the ribosomes, the sites of protein synthesis.

Transfer RNA (tRNA)

RNA that ferries amino acids to the ribosomes for protein synthesis and decodes mRNA's message.

Transcription

The process of transcribing DNA information into mRNA.

Translation

The process of decoding mRNA information to assemble polypeptides.