Compare, with examples, some ways in which cells may vary in appearance and function.
- Size: ex. μm to mm- Shape: ex. branches, boxy, rod, ever-changing (macrophages)- Chemical requirements: oxygen, carbon dioxide, sunlight, water, etc. Specialisation: some cells are specialised for production of hormones, starch, fat, latex, pigments, etc. Muscle cells burn fuel for mechanical work. Passing genetic info is for the egg and sperm
Outline, with examples, ways in which cells share a basic fundamental chemistry.
Cells are composed of the same sorts of molecules and participate in the same types of chemical reactions. Genetic information, in the form of genes, is carried in DNA molecules. Long polymer chains of DNA are made from the same set of four monomers (nucleotides) which is then transcribed into a set of polynucleotides called RNA. Most of this RNA is then translated into a proteinProteins are built from the same 20 amino acids (in different order) for every organism- gives protein a different conformation
Explain how the relationship between DNA, RNA, and protein—as laid out in the central dogma—makes the self-replication of living cells possible.
The sequence of nucleotides in a molecule of DNA dictates the sequence of amino acids in a protein. Proteins catalyse the replication of DNA, transcription of RNA, and participate in translation of RNA into proteins. It's a feedback loop
Summarize how the processes of mutation and selection promote the gradual evolution of individuals best suited for survival in a wide range of habitats.
Mutations change the sequence of nucleotides in the DNAStruggle for survival eliminates mutations that change organisms for the worst, favors mutation that change organisms for the better, and tolerates mutations that change organism in a neutral way
Explain how differentiated cell types can vary widely in form and function despite having the same genome sequence.
They all come from a single fertilised egg and contain identical DNA, but they express different genes. Some RNA and proteins are produced, while others are not depending on signals from other cells
List the three tenets of cell theory and explain their ramifications for the study of cell biology.
1. all organisms are made of cells. 2. all existing cells are produced by other living cells. 3. the cell is the basic structural and functional unit of living organismsFor cell biology, it means questions about the present are inescapably linked to conditions in the past
Contrast light microscopy, super-resolution fluorescence light microscopy, and electron microscopy in terms of the cell components that can generally be distinguished using each.
Light microscopy: plasma membrane, nucleus, cytoplasm, nothing smaller than 0.2 μm. Super-resolution fluorescence light microscopy: can see things as small as 20 nm, ex. ribosomeElectron microscopy: thin sections are cit and stained with electron dense heavy metals. Organelles and even singular large molecules can be seen. Fine structure of a cell can be seen
Compare how samples are prepared for light versus electron microscopy and explain how these preparations affect whether the technique can be used for viewing living cells or tissues.
- Light microscopes: cut a very thin slice from a suitable plant or animal tissue. Tissue has to be fixed (preserved by pickling in a reactive chemical solution), supported by embedding in a solid wax or resin, cut, or sectioned into thin slices, and stained before viewing- Electron microscopy: similar procedures but sections have to be much thinner. Can not look at living cells. They are stained with electron- dense heavy metals
Describe the structural differences between prokaryotes and eukaryotes.
-prokaryotes: only organelles are ribosomes, ex. bacteria- eukaryotes: have a nucleus
Analyze how eukaryotic cells and organisms rely on the function of prokaryotic cells and their descendants.
-mitochondria evolved from aerobic bacteria that took to living inside anaerobic ancestor's of today's eukaryotic cells- Plant's can't capture N2 from the atmosphere without bacteria
Compare prokaryotes and eukaryotes in terms of their relative preponderance on Earth, their range of habitat, and their tendency toward multicellularity.
-prokaryotes are single celled organisms, but some join to form chains, clusters, etc. They live in a big range of habitats, from hot puddles of volcanic mud to interior of other cells. They vastly outnumber eukaryotic organisms on earth
Justify the division of prokaryotes into bacteria and archaea.
DNA sequencing reveals that, at the molecular level, the members of these two domains differ as much from one another as either does from the eukaryotes
State the function of the nucleus and describe its structural features.
-prominent, rounded structure that contains the DNA of a eukaryotic cell-has two concentric membranes that form the nuclear envelope
Explain how the structure of the mitochondrion supports its function.
Mitochondria are generators of chemical energy for the cell. They harness the energy from the oxidation of food molecules, such as sugars, to produce ATP, which powers most of the cell's activities. Having a folded membrane allows greater surface area for this to happen
Outline the evolution of mitochondria and chloroplasts and cite the evidence for these origins.
- Mitochondria and chloroplasts both contain their own DNA and reproduce by dividing, similar to bacteria. - chloroplasts, in their bacteria form, are thought to have been taken up by early eukaryotic cells that already contained mitochondria
Explain how chloroplasts and mitochondria cooperate as plant cells convert light energy into chemical energy.
chloroplasts enable plants to gather their energy directly from sunlight. They allow plants to produce the food molecules- and the oxygen- that mitochondria use to generate chemical energy in the form of ATP
Compare the function of lysosomes and peroxisomes.
-Lysosomes: small, irregular shaped organelles in which intracellular digestion occurs, releasing nutrients from ingested food particles into cytosol and breaking down unwanted molecules for either recycling within the cell or excretion from the cell-peroxisomes: small, membrane-enclosed vesicles that provide a sequestered environment for a variety of reactions in which hydrogen peroxide is used to inactivate toxic molecules
Compare the structure, location, and function of the endoplasmic reticulum and Golgi apparatus.
-endoplasmic reticulum: an irregular maze of interconnected spaces enclosed by a membrane. where most cell-membrane components, as well as materials destined for export from the cell, are made. This organelle is enormously enlarged in cells that are special for secretion of proteins-Golgi apparatus: modifies and packages molecules made in the ER that are destined to be either secreted from the cell or transported from ingest food particles in to the cytosol and breaking down unwanted molecules for either recycling within the cell or excretion from the cell
Outline the role that transport vesicles play in endocytosis, exocytosis, and the movement of materials between one membrane-enclosed organelle and another.
transport vesicles ferry materials between one membrane- enclosed organelle and anotherThey pinch off from the membrane of one organelle and fuse with another, like tiny soap bubbles -endocytosis: portions of the plasma membrane tuck inward and pinch off to form vesicles that carry material captured from the external medium into the cell-exocytosis: vesicles from inside the cell fuse with the plasma membrane and release the contents into the external medium (most hormones and signal molecules that allow cells to communicate with one another are secreted from cells by exocytosis
Relate the location of the cytosol with respect to the cell's membrane-enclosed organelles.
-the part of cytoplasm that isn't contained within intracellular membranes-site of many chemical reactions fundamental to the cell's existence
List the three major filaments of the cytoskeleton and contrast the roles they have in animal cells.
-actin filaments (thinnest): responsible for muscle contraction-microtubules (thickest): minute hollow tubes that help pull the duplicated chromosomes apart and distribute them equally into two daughter cells-intermediate filaments: serve to strengthen most animal cells
Outline the role the cytoskeleton has in plant cells.
- mitochondria are driven in a constant stream around the cell interior along cytoskeletal tracks
Describe the ancestral cell that likely engulfed the aerobic bacteria that gave rise to mitochondria and explain why this event is thought to have preceded the acquisition of chloroplasts.
it was a predator that fed by capturing other cells. This would require a large size, a flexible membrane, and cytoskeleton to help the cell move and eat.- It is thought that mitochondria was acquired first because they are essentially the same in plants, animal, and fungi, so it probably happened before these lines diverged
Review why scientists study model organisms.
-All cells are thought to have descended from a common ancestor whose fundamental properties have been conserved through evolution so knowledge gained from the study of one organism contributes to our understanding of others-Some reproduce rapidly and are convenient for genetic manipulations; others are multicellular but transparent, so the development of all their internal tissues and organs can be viewed directly in the live animal.ex. mouse (represent mammals)ex. Saccharomyces cerevisiae (representing a unicellular eukaryote)ex. E. coli (represents bacteria)
Compare E. coli, S. cerevisiae, and A. thaliana and list the types of discoveries made by studying each.
- S. cerevisiae is a small, single-celled fungus that is at least as closely related to animals as it is to plants. Like other fungi, it has a rigid cell wall, is relatively immobile, and possesses mitochondria but not chloroplasts. When nutrients are plentiful, S. cerevisiae reproduces almost as rapidly as a bacterium.- A. thaliana: can be grown indoors in large numbers
Compare flies, worms, fish, and mice as model organisms and name a benefit of studying each.
-fruit flies: proved that genes were carried on chromosomesworms: develops with clockwork precision from a fertilised egg cell into an adult with exactly 959 body cells- helped us understand apoptosis
Review the benefits of studying cultured human cells.
Given the appropriate surroundings, many humans cell types-indeed, many cell types of animals and plants-will survive, proliferate, and even express specialized properties in a culture dish. These are said to be carried out in vitro ("in glass").However, experiments done on intact organisms are called in vivo ("in the living"). Because cultured cells are maintained in a controlled environment, they are accessible to study in ways that are often not possible in vivo.Cultured cells can be exposed to hormones or growth factors and the effects that these signal molecules have on the shape or behavior of the cells can be easily explored.
Assess the relationship between genome size and gene number.
In prokaryotes, it is a linear relationships. As genome size increases the number of genes increases at a disproportionately slower rate in eukaryotes
Explain the significance of homologous genes and proteins.
Genes and proteins are similar to homologous structures because to determine relationships among species biologists may look at similar genes and proteins. They may have the same proteins or genes but different uses like homologous structures.
Summarize the roles played by the nucleotide sequences contained in an organism's genome.
Nucleotide sequences (in sets of 3) code for the production of proteins, respective to the specific nucleotide sequence
Outline an experiment that would allow investigators to determine whether proteins from different eukaryotes are functionally interchangeable.
determine the nucleotide sequence found within the genome; search for homology between the two proteins??