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Lecture

Biology 1002B Lecture Notes - Chlamydomonas Reinhardtii, Physcomitrella Patens, Alpha Helix


Department
Biology
Course Code
BIOL 1002B
Professor
Tom Haffie

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Biology 1002B - Independent Study Outcomes & Lecture Outcomes
Lecture 1: Introducing Bio 1002B and Chlamydomonas
Independent Study Outcomes
1. Identify criteria used to measure complexity.
Criteria used to measure complexity include:
Genome size or the total number of genes in an organism
Gene (copy) number or the number of copies of a gene in a given gene family resulting from gene
duplication
Increase in the size of organisms over the course of evolution
The number of genes that encode proteins
The number of parts or units in an organism (where parts might be segments, organs, tissues, and so
forth)
The number of cell types possessed by an organism
Increased compartmentalization, specialization, or subdivision of function over the course of evolution
The number of gene, gene networks or cell-to-cell interactions required to form the parts or an organism
The number of interactions between the parts of an organism, reflecting increasing functional complexity
and/or integration over the course of evolution
2. Identify the main structural components of Chlamydomonas cells.
Chlamydomonas reinhardtii is a single-celled photosynthetic eukaryote that is commonly found in ponds and lakes.
Each cell contains a single large chloroplast that harvests light energy and uses it to make energy-rich molecules
through the process of photosynthesis. In addition, each cell contains a light sensor called an eyespot that allows
individual cells to gather information about the location and intensity of a light source.
Chlamydomonas reinharditii. Each cell
contains a single chloroplast used for
photosynthesis as well as an eyespot
for sensing light in the environment.

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3. Identify the relationship between Chlamydomonas and the evolutionary common ancestor of animals and
plants.
Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years
ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and
function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but
lost in land plants.
Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal
previously unknown genes associated with photosynthetic and flagellar functions, and establish links between
ciliopathy and the composition and function of flagella.
Chlamydomonas reinhardtii is a ~10-mm, unicellular, soil-dwelling green alga with multiple mitochondria, two
anterior flagella for motility and mating, and a chloroplast that houses the photosynthetic apparatus and critical
metabolic pathways. Chlamydomonas is used to study eukaryotic photosynthesis because, unlike angiosperms
(flowering plants), it grows in the dark on an organic carbon source while maintaining a functional photosynthetic
apparatus. It also is a model for explaining eukaryotic flagella and basal body functions and the extreme effects of
their dysfunction. The Chlorophytes (green algae, including Chlamydomonas and Ostreococcus) diverged from the
Streptophytes (land plants and their close relatives) over a billion years ago. These lineages are part of the green
plant lineage (Viridiplantae), which previously diverged from opisthokonts (animals, fungi, and Choanozoa). Many
Chlamydomonas genes can be traced to the green plant or plant-animal common ancestor by comparative
genomic analyses. Specifically, many Chlamydomonas and angiosperm genes are derived from ancestral green
plant genes, including those associated with photosynthesis and plastid function; these are also present in
Ostreococcus spp. and the moss Physcomitrella patens. Genes shared by Chlamydomonas and animals are derived
from the last plant-animal common ancestor and many of these have been lost in angiosperms, notably those
encoding proteins of the eukaryotic flagellum (or cilium) and the associated basal body (or centriole).
This analysis of the Chlamydomonas genome sheds light on the nature of the last common ancestor of plants and
animals and identifies many cilia (flagellum) and plastid (chloroplast) related genes.
Plastid - A double membrane bound organelle involved in the synthesis and storage of food, and is commonly
found within the cells of photosynthetic organisms, like plants (chloroplast)
Lecture Outcomes

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Lecture 2: Light
Lecture Outcomes
Lecture 3: Protein Structure & Function
Independent Study Outcomes
1. Basic structure of an amino acid and what are the different classes of amino acids.
An amino acid contains a central carbon bonded to a carboxyl group, an amino group, an r-group, and a
hydrogen. The r-group is what varies between the 20 amino acids and gives them unique characteristics. The
covalent bonds between amino acids are called peptide bonds. It is a bond between the carboxyl group of one
amino acid and the amino group of another amino acid. Amino acids are bonded through condensation
reactions, which produces a water molecule.
The basic structure of an amino acid is a carbon chain with an amino group (NH2) at one end, and a carboxyl
group (-COOH) at the other. The differences between amino acids lies in the carbon chain in the middle; it can
be as simple as one carbon or as complex as many carbon atoms with branches and forks. Side groups can be
added, such as sulphur.
Each amino acid contains a carboxyl group, an amino group and a variable side group (R). These all connect to
a central carbon, termed the α-carbon
Amino acids have a two-carbon bond. One of the carbons is part of a
group called the carboxyl group (COO-). A carboxyl group is made up of
one carbon (C) and two oxygen(O) atoms. That carboxyl group has a
negative charge, since it is a carboxylic acid (-COOH) that has lost
its hydrogen (H) atom. What is left the carboxyl group is called
a conjugate base. The second carbon is connected to the amino group.
Amino means there is an NH2 group bonded to the carbon atom. In the
image, you see a "+" and a "-". Those positive and negative signs are
there because, in amino acids, one hydrogen atom moves to the other
end of the molecule. An extra "H" gives you a positive charge.
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