Biology Class Quiz on Cell Functions

Prokaryotic Cell Structures

• A prokaryotic cell is a simple, single-celled organism lacking a nucleus and membrane-bound organelles.
• Cell wall: A rigid outer layer providing support and protection. It is composed of peptidoglycan, a type of polysaccharide and polypeptide.
• Capsule: A slimy layer outside the cell wall, offering protection against dehydration and the host's immune system.
• Plasmid: A small, circular DNA molecule separate from the main chromosome. It often carries genes for antibiotic resistance or other beneficial traits.
• Flagellum: A whip-like appendage used for motility.
• Pili: Thin, protein tubes enabling the bacteria to adhere to surfaces.
• Ribosomes: Involved in protein synthesis.
• Mesosomes: Infoldings of the cell membrane, playing a role in respiration.
• Circular DNA: The main genetic material of the cell, located in the cytoplasm.

Eukaryotic Cell Structures

• A eukaryotic cell is a complex cell with a nucleus and membrane-bound organelles.
• Nucleus: Contains the cell's DNA and controls cellular activities. The nucleus is enclosed by a double membrane called the nuclear envelope.
• Nucleolus: A darker region inside the nucleus, responsible for ribosome production.
• Ribosomes: Involved in protein synthesis, found in the cytoplasm or on the rough endoplasmic reticulum.
• Rough endoplasmic reticulum (rER): A system of membrane-bound channels studded with ribosomes for protein synthesis and transport.
• Smooth endoplasmic reticulum (sER): A system of membrane-bound channels involved in lipid synthesis and detoxification.
• Mitochondria: Organelles responsible for cellular respiration, producing ATP (energy). They consist of an outer and inner membrane. The inner membrane is folded into cristae to increase surface area.
• Centrioles: Involved in cell division, forming the spindle apparatus. They are microtubule-based structures.
• Lysosomes: Contain digestive enzymes for breaking down cellular waste and unwanted materials. Their spherical shape is bound with a membrane.
• Golgi apparatus: Modifies, sorts, and packages proteins and lipids for transport to other parts of the cell. It is a stack of flattened, membrane-bound sacs and vesicles.

Cell Cycle

• Interphase (G1, S, G2): The cell prepares for division.
  • G1: Cell growth, increase in cytoplasm, proteins, and organelles.
  • S: DNA replication occurs.
  • G2: Cell continues to grow and prepares for mitosis. Centrioles replicate, and spindle fibers start to form.
• Mitosis: Nuclear division: One nucleus divides into two identical nuclei.
• Cytokinesis: Cell division. The cytoplasm divides, producing two identical daughter cells.

Meiosis

• Meiosis is a type of cell division that produces gametes (sex cells) containing half the number of chromosomes as the parent cell.
• Chromosomes replicate before division, and homologous chromosomes pair up during prophase I.
• Meiosis I: Homologous chromosomes pair and separate.
• Meiosis II: Sister chromatids separate.
• Genetic variation: Meiosis produces variation through crossing over and independent assortment.

Cell Structures from Photographs/Electron Micrographs

• The provided images show various cell structures. Students should be able to identify different organelles based on their appearance in the images.

Protein Production and Trafficking

• A flow chart demonstrates how various organelles and molecules are involved in protein production and trafficking in a cell.
  • Transcription of DNA to mRNA
  • mRNA exiting the nucleus
  • Translation on ribosomes to produce polypeptide
  • Transfer to the endoplasmic reticulum
  • Modification and packaging in the Golgi apparatus
  • Transport to various destinations
  • Secretion outside the cell, if needed

Ovum

• An ovum (egg cell) is a large, spherical cell containing cytoplasm, haploid nucleus, and lysosomes.
  • Haploid nucleus: Contains half the number of chromosomes as a diploid nucleus.
  • Cytoplasm: Contains cytoplasm.
  • Lysosomes: Enzymes for changes to the zona pellucida.
  • Follicle cells: Cells surrounding the ovum and releasing chemicals, triggering the acrosome reaction.
  • Jelly-like coating (zona pellucida): Protection.
  • Lipid droplets: Energy reserve for the developing embryo.

Sperm

• Sperm is a small, mobile cell containing a haploid nucleus, acrosome, and mitochondria.
  • Haploid nucleus: Contains half the number of chromosomes as a diploid nucleus
  • Acrosome: Modified lysosome for digesting the zona pellucida during fertilization.
  • Mitochondria: Generate energy in the form of ATP for the flagellum
  • Flagellum: Enables sperm movement towards the ovum
  • Head, middle section: Structures that contain the necessary parts for movement and fertilization

Fertilization

• Fertilization is a process where sperm fuses with an ovum to initiate the development of a new organism.
  • Sperm reaches the ovum
  • Chemicals trigger acrosome reaction
  • Digestive enzymes digest outer layers
  • Sperm nucleus enters ovum, fusing with the ovum's nucleus
  • Cortical reaction for preventing polyspermy(multiple sperm entry)

Chromosome, Homologous Pair, Gamete, Haploid, and Diploid

• Gene: Segment of DNA coding for a protein
• Allele: One form of a gene
• Locus: Position of a gene on a chromosome
• Phenotype: Observable characteristics (e.g., eye color)
• Genotype: Set of alleles(e.g., BB, Bb, or bb)
• Gamete: Sex cell(sperm or ovum), haploid
• Haploid: Single set of chromosomes
• Diploid: Two sets of chromosomes

Gametes and Haploid Cells

• Gametes must be haploid (containing one set of chromosomes) for fertilization. Failure to reduce the chromosome number in gametes would result in a doubling of chromosome number in each generation with the possible consequences of defects.

Steps to Answer a Describing Data Question

• Understand the question and the data to be described.
• Describe patterns and general trends in the data, using relevant terminology.
• Focus on the aspects that are relevant.
• Use precise data to support your reasoning and be precise in the use of vocabulary.
• Quantify trends whenever possible.
• Be systematic in approach, ensuring to describe all aspects of the data rather than just what first appears to be the case.

Stages of Interphase

• G1: Cell growth and preparation for DNA replication. Organelles and cell components are produced.
• S: DNA synthesis and replication takes place.
• G2: Cell growth, synthesis of proteins and organelles required for mitosis. DNA is checked for errors.

Stages of Mitosis

• Prophase: Condensation of chromosomes, breakdown of the nuclear envelope, and formation of the spindle apparatus.
• Metaphase: Alignment of chromosomes at the metaphase plate (equator of the cell) and attachment of spindle fibers to the centromeres.
• Anaphase: Separation of sister chromatids and movement to opposite poles of the cell.
• Telophase: Decondensation of chromosomes, re-formation of the nuclear envelope, and cytokinesis (cytoplasm division).

Determining the Stage of the Cell Cycle from a Photograph or Diagram

• Visually assess the appearance of chromosomes, the presence or absence of a nuclear envelope, and the arrangement of chromosomes to determine stage.

Preparing Cells from Garlic Root Tips

• Gather garlic root tips
• Place tips in acid to separate the cells
• Place on a slide
• Gently break up the material
• Stain with toluidine blue
• Cover and press firmly to squash
• Count the number of cells for each stage of mitosis

Totipotent, Pluripotent, Multipotent, Stem Cell, and Differentiated

• Totipotent: Cells capable of developing into any cell type in an organism, including the extra-embryonic tissues(e.g. placenta)
• Pluripotent: Cells capable of developing into most cell types in an organism.
• Multipotent: Cells capable of developing into a limited number of cell types.
• Stem cell: Undifferentiated cells that can divide to produce more stem cells and differentiate into specialized cells.
• Differentiated: Specialized cells with a particular function.

Zygote Development into Blastocyst

• A zygote develops into a blastocyst through cell division.
• The blastocyst contains an inner cell mass (ICM), that will develop into the embryo, and trophoblast cells that will form the placenta.
• A fluid-filled blastocoel cavity is present.

E. coli and Genetic Switches

• E. coli uses genetic switches (repressor proteins) to respond differently to the presence or absence of lactose.

  • When lactose is absent, a repressor protein blocks the pathway for lactose metabolism.
  • When lactose is present, lactose binds to the repressor protein, inactivating it.

• RNA polymerase can then bind to the promoter region and initiate transcription.

RNA Polymerase and Gene Transcription

• Gene transcription occurs when RNA polymerase binds to the promoter region of a gene.

• Specific signals, including regulator proteins, determine if the promoter is available for binding.

Defining Genetics, Epigenetics, Genome, and Epigenome

• Genetics: Study of genes and inheritance
• Epigenetics: Study of heritable changes in gene expression without changes to the DNA sequence
• Genome: Complete set of genes in a cell's DNA
• Epigenome: Chemical tags on DNA or histones affecting gene expression and are crucial for controlling gene activity without altering DNA.

DNA Methylation and Gene Expression

• DNA methylation adds a methyl group to a base within DNA, usually impacting gene expression by silencing genes. This process involves methylation of cytosine or adenine bases, leading to gene repression.

Histone Modification and Gene Expression

• Histone acetylation, adds acetyl groups to histone proteins, loosening chromatin structure to facilitate access for transcription factors and RNA polymerase, leading to gene activation.

Test your knowledge on cell biology with this quiz focusing on cell structures and functions. Topics include mitochondria, organelles, and meiosis. Perfect for biology students looking to enhance their understanding.