Biology Chapter 1: Cell Structure and Function Quiz

Biology 1 - Cells, Molecular Biology, and Genetics (Biol 1000)

• This course covers cells, molecular biology, and genetics.
• The professor is Dr. Michael Cardinal-Aucoin.
• The course is for Winter 2025.
• The school is York University.

Evolution

• Evolution is a major unifying theory in biology.
• Darwinian evolution describes natural selection.
• Evidence and examples of evolution were discussed.

Major Unifying Concepts Of Biology

• Theory of Evolution by Natural Selection
• Cell Theory
• Genetics
• Homeostasis

A Note about Theories

• In everyday language, "theory" often means a guess or speculation.
• In science, a theory is a broad explanation supported by multiple lines of evidence.
• Scientific theories have withstood rigorous testing.

Two Major Unifying Concepts of Biology

• Theory of Evolution by Natural Selection:
  • Characteristics of a population change over time (pattern).
  • Individuals with certain traits produce more offspring than those without (mechanism).
  • All species are related by descent from a common ancestor.
  • All species come from pre-existing species.
• Cell Theory:
  • All organisms are made up of cells (pattern).
  • All cells come from pre-existing cells (mechanism).
  • All cells in a multicellular organism descend from an ancestral cell.

Modern Cell Theory

• A cell is the smallest self-reproducing unit of life.
• Cells make up all living things.
• New cells arise from pre-existing cells.
• The activity of an organism depends on the total activity of independent cells.
• Energy flow occurs within cells.
• Cells contain hereditary information (DNA and RNA).
• Cells of similar organisms share similar chemical composition.

Cells

• All cells share certain properties, but not all are identical.
• Plant cells, animal cells, and bacteria were shown.

Different Types of Cells

• Four basic features of all cells:
  • Plasma membrane
  • Cytosol (semifluid substance)
  • Genetic material (at some point)
  • Ribosomes (to make proteins)

Units of Measure

• Micrometer (µm): 1,000,000 µm = 1 meter; e.g., strand of hair has diameter ~20-180 µm
• Nanometer (nm): 1,000,000,000 nm = 1 meter; e.g., wavelength of visible light ~400-700 nm
• Angstrom (Å): 10,000,000,000 Å = 1 meter; used to measure atoms/bond lengths

Introduction to the Cell

• A diagram showing the relative sizes of various biological entities on a logarithmic scale was presented.

Why Study Cells?

• Cells are the fundamental functional units of all living things.
• Cell theory is a unifying principle in biology.
• Understanding cells provides insight into the functions of organisms (e.g., plants, animals, parasites, fungi).
• Knowledge of cells is essential for understanding human health and diseases.
• Knowledge of cells important for treatments development.

Evolution by Natural Selection

• Differences exist between individuals within a population.
• These differences are heritable, passed from one generation to the next.
• Some individuals leave more offspring than others.
• Over time these differences in population change based on reproduction and differential survival.

Natural Selection Mechanisms

• Artificial selection (by humans)
• Sexual selection (competition for mates)
• Genetic drift (random chance)
• Gene flow (movement between populations)

Evidence for the Theory of Evolution by Natural Selection

• Many visuals of evidence of the theory in several forms were included (e.g., examples, pictures, etc)

Darwin's Quote

• "It is not the strongest of the species that survives, nor the most intelligent, but the one most adaptable to change."

How Natural Selection Works

• Environmental resources are limited, so organisms compete for them.
• Organisms vary extensively in traits.
• Beneficial traits provide an advantage.
• Individuals with advantageous traits leave more offspring.
• Heritable beneficial traits become more common over time.
• The population evolves.

Genotype and Phenotype

• Genotype: genetic makeup of an organism
• Phenotype: observable characteristics resulting from the interaction of genotype and environment

Evolution, Genotype, Phenotype, Environment

• Evolution is the interplay between genotype, phenotype, and the environment.
• Genotype influences phenotype.
• Environmental influences affect phenotype.
• Through evolution, advantageous characteristics become increasingly frequent in a population.

Macroevolution and Microevolution

• Macroevolution represents large-scale changes that occur over millions of years, and result from many incremental modifications.
• Microevolution involves small-scale changes within a population's traits over relatively short periods.

The Vastness of Evolutionary Time

• Estimates for the age of the Earth, human generations, etc. were presented in the context of evolutionary time.

Evidence for Evolution

• Extensive evidence supports evolution through homology, universal genetic code, fossils, genomics, insecticide resistance, and biogeography.

Biogeography and Species Distributions

• Species are more closely related to those in the same geographic area.
• Geographic distribution reflects divergence from common ancestors into different habitats.

Fossil Record

• Oldest fossils from around 4 billion years ago (mya)
• Cyanobacteria (blue-green algae): oldest fossils in the Precambrian Period.
• Cyanobacteria also formed large layered structures called stromatolites.
• Fossils of single-celled eukaryotes around 1.8 bya.
• Multicellularity occurred around 1.8 to 1.5 bya.
• Evolution created varied species through multiple lineages over time.

How is Evolution Relevant to Cell Biology?

• Understanding the evolution of cells

  • How cells evolved.
  • Their history
  • The diversity of cells
  • Common features of cells

• How cells have adapted to various environments

Main Events in the Evolution of Cells

• Abiogenesis (first life)
• Protocells (early life forms)
• RNA world (early genetic material)
• Prokaryotes (first cells)
• Endosymbiosis (origin of eukaryotic organelles)
• Eukaryotes (cells with nuclei)
• Multicellularity (formation of complex organisms)

Abiogenesis

• Prebiotic synthesis- molecules forms spontaneously.
• No fossil records but can study in lab.
• Molecules of life can be formed through lab conditions replicating early earth conditions.

Protocells

• Formation of micelles and liposomes as chemical products resulting in the formation of the first cells
• Hydrophilic heads together, and hydrophobic tails together.

RNA World

• RNA has properties of both DNA and proteins.
• Many scientists think RNA, not DNA, was the first genetic material on Earth.

Prokaryotes

• Small, simple cells without internal compartments.
• Evolved most biochemistry that is present in life forms today
• DNA replication/genetic code
• Protein synthesis
• Photosynthesis
• Anaerobic and aerobic metabolism

Endosymbiosis

• Some organelles (e.g. mitochondria and chloroplasts) likely evolved from free-living prokaryotes that were engulfed by larger cells.

Eukaryotes

• Cells with nuclei and other internal compartments
• Larger than prokaryotic cells
• More complex structures and functions
• True multicellularity
• Multiple chromosomes, mitosis, meiosis, and increased genetic diversity

Multicellularity

• First multicellular organisms appeared around 2.7 billion years ago (bya).
• Multicellularity arose multiple times.
• Strong selective advantage over time.

Advantages of Multicellularity

• Increased size
• Competition for food
• Protection from predators
• Division of labour
• Increased complexity
• Overcome limits to cell size

Eukaryotes as Evolution's Major Achievement

• Eukaryotic cells are evolution's major achievement, building upon prokaryotic cells

Test your understanding of basic cell features and their significance in biology. This quiz covers essential concepts regarding cellular structures, functions, and their roles in living organisms. Ideal for students studying cell biology and related topics.