Prokaryotes, Eukaryotes, Tissues, Cells and the Cell Cycle

Study flashcards covering the basics of prokaryotic vs eukaryotic cells, animal and plant tissues, modified cells, DNA and chromosomes, and the cell cycle including mitosis and meiosis.

What is a prokaryotic cell?

A cell that lacks a nucleus and membrane-bound organelles.

What is a eukaryotic cell?

A cell that has a nucleus and membrane-bound organelles.

What is the key distinguishing feature regarding the nucleus in prokaryotic vs eukaryotic cells?

Prokaryotic cells have no nucleus (DNA in the nucleoid region); eukaryotic cells have a nucleus enclosed by a nuclear membrane.

What is the composition of prokaryotic cell walls?

Peptidoglycan.

What are the walls of plant and fungal cells made of?

Plant cell walls: cellulose; fungal cell walls: chitin.

What lipids or molecules are characteristic of prokaryotic vs eukaryotic membranes?

Prokaryotic membranes contain hopanoids; eukaryotic membranes contain sterols such as cholesterol, phytosterol, or ergosterol.

Do prokaryotic cells have an endomembrane system?

No; prokaryotes lack membrane-bound organelles and an endomembrane system.

How is prokaryotic DNA organized?

Circular DNA, not wrapped in histones; usually one chromosome and may have plasmids.

How is eukaryotic DNA organized?

Linear DNA wrapped around histones and found in multiple chromosomes.

How is the DNA of prokaryotes typically arranged in terms of chromosomes and plasmids?

Usually a single circular chromosome with possible plasmids.

What are the typical cell sizes for prokaryotes vs eukaryotes?

Prokaryotes: about 0.1–5 μm; eukaryotes: about 10–100 μm.

What is the difference in cellularity between prokaryotes and eukaryotes?

Prokaryotes are unicellular; eukaryotes can be unicellular or multicellular.

How do prokaryotes and eukaryotes reproduce?

Prokaryotes reproduce by binary fission (or spores); eukaryotes reproduce by mitosis (somatic cells) and meiosis (gametes).

Where do transcription and translation occur in prokaryotes and do they contain introns?

In prokaryotes, transcription and translation occur in the cytoplasm and there are generally no introns.

Where do transcription and translation occur in eukaryotes and what happens to introns?

Transcription in the nucleus, translation in the cytoplasm; introns are removed during processing.

What are the four basic tissue types in animals?

Epithelial, Connective, Muscle, Nervous.

What is the primary function of epithelial tissue?

Forms the inner and outer lining of organs, body surfaces, and glandular tissue.

What is the primary function of connective tissue?

The most abundant tissue; it supports, connects, and protects body parts and contains extracellular matrix.

What makes up the extracellular matrix in connective tissue?

Ground substance and fibers such as collagen, elastin, and reticular.

What is the extracellular matrix?

Material outside cells composed of ground substance and fibers in connective tissues.

What is elastin?

A rubber-like protein fiber that stretches and recoils.

What is collagen?

The thickest and strongest fiber in connective tissue.

What are reticular fibers?

Thin fibers forming mesh-like structures in organs such as the spleen.

Name the three types of muscle tissue.

Skeletal muscle, Smooth muscle, Cardiac muscle.

What are the characteristics of skeletal muscle?

Voluntary, striated, multinucleated; attached to bones; enables movement.

What are the characteristics of smooth muscle?

Involuntary; found in hollow organs like intestines and blood vessels.

What are the characteristics of cardiac muscle?

Involuntary; found in the heart; striated and uninucleated; contains intercalated disks with gap junctions.

What is the function of intercalated disks in cardiac muscle?

Facilitate synchronized contractions by connecting cardiac muscle cells.

What are the main components of nervous tissue?

Neurons and supporting neuroglia cells.

What is the basic functional unit of the nervous system?

Neuron.

What are dendrites and what do they do?

Dendrites are extensions that receive signals and send them to the cell body.

What is the function of the axon?

Transmits signals away from the cell body to other neurons or effectors.

What are astrocytes?

Glial cells in the CNS that support neurons and maintain chemical balance.

What are microglial cells?

Glial cells in the CNS that act as phagocytes to remove waste.

What are ependymal cells?

Line the cavities of the brain and spinal cord with cilia.

What are oligodendrocytes?

Glial cells in the CNS that produce the myelin sheath.

What are satellite cells?

Glial cells surrounding neuron cell bodies in the PNS; regulate the neuronal environment.

What are Schwann cells?

Produce the myelin sheath in the PNS and aid in nerve regeneration.

What are plant tissues and how are they classified?

Groups of cells in plants performing specific functions; classified as meristematic and permanent tissues.

What are meristematic tissues?

Actively dividing cells found in growing parts; produce new cells for growth.

Where are apical meristems located and what do they produce?

At the tips of roots and shoots; produce primary meristems that give rise to dermal, vascular, and ground tissues.

What are lateral meristems responsible for?

Increase in diameter (secondary growth); located in vascular and cork cambium.

What are simple permanent tissues?

Formed from matured meristematic tissues; include epidermal tissues.

What are epidermal tissues?

Outer protective covering derived from protoderm; usually covered by a waxy cuticle.

What are root hairs?

Tiny projections of the root epidermis that increase surface area for absorption.

What are trichomes?

Hair-like structures on leaves and stems that reflect light and reduce water loss.

What are guard cells?

Specialized epidermal cells that regulate stomatal opening for gas exchange.

What is parenchyma tissue?

Least specialized ground tissue with thin, flexible walls; involved in photosynthesis and starch storage.

What is collenchyma tissue?

Ground tissue with unevenly thickened primary walls; provides flexible support.

What is sclerenchyma tissue?

Ground tissue with thick, lignified secondary walls; provides rigid support.

What are xylem and phloem?

Complex permanent tissues; xylem conducts water/minerals; phloem conducts sugars and other organic compounds.

What are meristematic and permanent tissues collectively responsible for in plants?

Growth, support, and transport.

What are modified or specialized animal cells such as cilia, stereocilia, and flagella used for?

Cilia aid movement; stereocilia aid sensing; flagella provide movement.

What are basal infoldings in animal cells for?

Aid in fluid transport.

What plant cells are involved in protecting leaves and stems and may reflect light?

Trichomes.

What plant cells increase water absorption in roots?

Root hairs.

What plant cells perform photosynthesis in leaves?

Mesophyll cells.

What plant tissues are used for transport of water and food?

Xylem and Phloem.

What is DNA and what is its basic structure?

DNA is the molecule of genetic information; double helix made of nucleotides.

What is a nucleotide?

The repeating unit of DNA that forms base pairs.

What is chromatin?

DNA wrapped around histone proteins in the nucleus during interphase.

What is a nucleosome?

DNA wrapped around histone proteins; basic unit of DNA packaging.

What is a histone?

Positively charged proteins around which DNA is wrapped to form nucleosomes.

What is a chromosome?

A condensed form of DNA that appears during cell division.

What are homologous chromosomes?

Pairs of chromosomes in diploid organisms that are similar but may have slight differences.

What is the diploid number (2n)?

The total number of chromosomes in a diploid cell (e.g., 46 in humans).

What is a chromatid?

One of two identical copies of a duplicated chromosome.

What are sister chromatids?

Two identical chromatids connected at the centromere.

What is a centromere?

Region where sister chromatids are joined; contains kinetochores for spindle attachment.

What is life cycle and what is cell cycle?

Life cycle is the sequence of stages in an organism's life; cell cycle is the set of stages a cell goes through to grow and divide.

What is interphase and which phases does it include?

Interphase is the phase where the cell grows and DNA is replicated; includes G1, S, and G2.

What happens in the G1 phase?

Cell growth and organelle doubling.

What happens in the S phase?

DNA replication.

What happens in the G2 phase?

Second growth phase between DNA replication and cell division.

What is mitosis?

Division of the nucleus to produce two identical nuclei.

What is meiosis?

Specialized cell division that produces gametes; reduces chromosome number by half.

What is a gamete?

Sex cell (sperm or egg).

What is fertilization?

Fusion of two gametes to form a zygote.

What is a zygote?

A single cell formed from fertilization.

What is a somatic cell?

Any body cell that is not a gamete.

What does haploid mean?

Having one complete set of chromosomes (n).

What does diploid mean?

Having two complete sets of chromosomes (2n).

What are triploid, tetraploid, and dodecaploid organisms?

Organisms with 3n, 4n, or 12n chromosome sets.

What are the stages of meiosis I?

Prophase I, Synapsis, Prometaphase I, Metaphase I, Anaphase I, Telophase I.

What is synapsis?

Pairing of homologous chromosomes during prophase I to form tetrads.

What happens in meiosis I?

Homologous chromosomes separate to form two haploid cells.

What are the stages of meiosis II?

Prophase II, Prometaphase II, Metaphase II, Anaphase II, Telophase II.

What happens to sister chromatids in meiosis II?

Sister chromatids separate, producing four haploid daughter cells.