BSCI 124  

BSCI 124
Plant Biology for Non-Science Majors


Glossary (in order of topics):


Spring 2004 Syllabus
Lecture Presentations
Sample Exam Questions
Extra Credit Plant Project (PDF)

Glossary Terms

Study Suggestions

BSCI 125 Lab


Variables - Factors which may or may not influence the outcome of an experiment
Control- A parallel experiment where one variable is changed so that it may be determined whether that variable affects the outcome
Epidermis- A tissue in plants which is normally the outermost layer of cells used for protection. This layer normally does not perform photosynthesis
Vascular tissues- A tissue which functions to transport water and sugars throughout the plant. Made up of :
  Xylem - A tissue which functions to transport water, normally from the roots upward
Phloem- A tissue which transports sugars from areas of the plant where they are made to areas which need sugar
Trichome -A leaf hair. An extension of epidermal cells to provide protection from drying or insects
Stoma (plural stomata) - An opening formed in the epidermal layer of the leaf by specialized cells to allow air to enter the leaf. These cells can open and close the hole to regulate the uptake of air and the loss of water through evaporation (transpiration)
Root hair - An extension of epidermal cells on the root which increases the contact between the root and soil to pick-up water and minerals from the soil
Ground tissue - A tissue which is usually internal to the plant and provides specialized functions- seed cortex, pith, parenchyma
  Cortex - A ground tissue which is beneath the epidermis in plant stems and root. It functions to store water and starch for the plant. In green stemmed plants, it also functions to provide photosynthesis
Pith - A ground tissue which is in the center of stems . It functions to store water and starch for the plant.
Palisade parenchyma (or mesophyll) - ground tissue in the leaf which functions as the main photosynthetic cells. They are packed closely together beneath the top epidermal cells for maximum absorption of the light.
Spongy parenchyma (or mesophyll) - ground tissue in the leaf which function in photosynthesis. This layer occurs in the bottom half of the leaf and so receives less light than the palisade parenchyma cells. Large air spaces between the cells provide a means for air and water transport between cells.
Polymer- a chain of similar compounds (building blocks) linked together
Lipids - A group of polymers built from fatty acids fatty acids. The long carbon chains in the fatty acids are hydrophobic (repel water) and so lipids usually separate from water and form membranes or droplets
Carbohydrates- A group of polymers whose building blocks are monosaccharides. Monosaccharides are single sugars (e.g. glucose), disaccharides are two linked sugars (e.g. sucrose), starch, glycogen and cellulose are polysaccharides of many glucose units linked together.
Proteins- a group of polymers made from amino acids linked end to end. The chemical properties of a protein are determined by the type and order of the amino acids. Proteins function as catalysts of specific chemical reactions
Nucleic Acids- a group of polymers made up from nucleotide bases (A, G, C, T, U) linked end to end. DNA is used for storing information, RNA is a gene-size copy of the information from DNA which is exported from the nucleus to produce a protein. Information in nucleic acids is transferred by the A-T and G-C pairing rule.
Membranes- lipid layer which prevent movement of compounds from one side to another and so forms compartments. Outer membrane separates cell from outside; inside, membranes form organelles
Cell wall- outer layer of plant cells made of cellulose, pectin (both carbohydrates) and lignin. It provides structural strength to the cell.
Cytoplasm- watery gel-like material inside cell between organelles
Organelles- compartments inside the cell which perform specialized functions:
  -nucleus: stores DNA, genetic information for building cell
-chromosomes are packaged DNA
-mitochondria: used for converting sugar to energy
-chloroplast: performs photosynthesis, only found in plants
-vacuole: storage closet of cell: acids, pigments, chemicals
Respiration - The entire process where sugar is “burned” to produce carbon dioxide. The energy released is saved as chemical energy in the form of ATP and NADH. The three parts are:
  Glycolysis- the splitting of the six carbon sugar into two three carbon compounds. Releases only part of the energy but can take place in the absence of oxygen
Kreb cycle- part of respiration where the three carbon compound (from glycolysis) is split into three molecules of carbon dioxide (CO2)- a one-carbon compound. Energy is obtained in the form of NADH.
Electron transport- the process where the electron transfer from NADH to oxygen (O2) is used to convert energy stored in NADH into energy stored as ATP. Needed to complete the extraction of energy in respiration.
Photosynthesis- The process where the energy in light is captured to convert carbon dioxide into sugar. The parts are:
  Light reaction- Chlorophyll ( a pigment) absorbs light and starts a process of electron transfers between proteins in the chloroplast. These result in the production of ATP and NADPH to store the energy. Chlorophyll takes an electron from water to replace its lost electron, producing oxygen (O2).
Dark reaction - the process which uses the energy stored as ATP and NADPH to combine CO2 (one carbon) into sugars (six-carbon compounds).
C4 plants- Plants which “pump” fixed carbon dioxide into cells in the leaves so as to increase effective CO2 levels in photosynthesis. Makes plants more efficient under hot dry, bright conditions since CO2 levels are limiting for photosynthesis.
Energy cycle- the movement of energy from sunlight into plants and transfer in the food chain. Results in the cycling of carbon from carbon dioxide into organic molecules like carbohydrates.
Gene - a segment of DNA which encodes a single protein (start, chain of amino acids, stop)
Codon- a set of three nucleotides which encodes a specific amino amino acid to be placed in a protein. Also punctuation (start, stop) codes. Together, the 81 possible codons form the genetic code.
Transcription- the copying of information from a gene-length piece of DNA into RNA. Uses the A-T G-C pairing to copy information.
Translation- the expression of the code of a gene encoded as nucleotide sequence in RNA into the corresponding amino acid sequence in a protein. Uses ribosomes (proteins) and tRNA (an adapter has nucleotide triplet and attached to specific amino acid) to perform the copying through A-T and G-C pairing
Genome- the entire set of genes in an organism which are encoded in the DNA in each cell
Chromosome- a physical segment of the genome, similar in principle to volumes of an encyclopedia
Meristerm- a point in the plant where cells divide, produces growth of the plant
Mitosis- the division of the DNA of the cell such that a dividing cell can produce two cells with exactly the same information in each cell.
Meiosis- a process used in sexual reproduction to produce 4 cells which contain only one homologous chromosome of each type. Forms gametes (pollen, ovules) used for fertilization.
Sister chromatids- Exact copies of a specific chromosome. Often are joined together until mitosis or meiosis separates them.
Homologous chromosomes- set of two similar chromosomes. Encode the same types of genes, but the exact information may be different. Individuals usually inherit one from the male parent and the other from the female parent
Diploid -a state of a cell having complete sets of two homologous chromosomes (2n)
Haploid - a state of a cell having a single set of chromosomes (n)
Gametes - a haploid reproductive cells - sperm and eggs, pollen and ovules
Zygote - a fertilized egg or ovule- usually diploid
Phenotype - appearance of an individual - how the information is expressed
Genotype - genetic makeup- the information at each allele
Alleles - DNA sequence information that encodes a different phenotype for a particular
gene (e.g. blue and brown eyes encoded by one gene that determines eye color)
Homozygous individuals - having identical alleles (one from each parent) for a particular characteristic
Heterozygous individuals- having two different alleles for a particular characteristic
Dominant allele- an allele of a certain gene which is able to hide another allele in a heterozygous individual
(e.g. purple allele in the pea)




Spring 2004
Dr. Edgar Moctezuma

University of Maryland

Department of Cell Biology & Molecular Genetics
College of Life Sciences | University of Maryland, College Park