Lab Terms (A-Z)

Allele

alternative version of a gene; e.g either dominant or recessive

Alternation of generation

a life cycle with distinct multicellular haploid and diploid stages found in some plants (ex: ferns)

Antheridium

male reproductive organ on the fern gametophyte in which the flagellated sperm cells are formed

Archegonium

female reproductive organ on the fern gametophyte in which egg cells are formed

Autosomal

refers to genes that are located on autosomes

Autosome

the non-sex chromosomes; in humans there are 22 pairs

Binary fission

a means of aesexual reproduction in prokaryotes in which a cell divides to form two identical organisms; “the bacterial mitosis”

Biotechnology

the use of living organisms or their components (such as DNA or protein) to make, modify, or process products for human benefit

Capsule 

a type of protective outer covering (glycocalyx) composed of polysaccharides found outside of the cell wall on many bacterial cells; protects bacteria from adverse conditions, digestion, dehydration 

Carotenoid

yellow, orange, and red pigments that are produced by chromoplasts in some plant cells

Carrier

refers to an individual who has the recessive allele for a condition or disease but does not express any symptoms of the condition or disease (the individual would be heterozygous for the trait)

Cell cycle

the regular cycle of events that a cell undergoes during growth and division; comprised of interphase (G1, S, and G2 phases) and cell division (mitosis and cytokinesis) 

Cell membrane (plasma membrane)

selectively permeable membrane that separates a cell’s contents from the surrounding environment and regulates passage of substances into and out of the cell

Cell plate

a new cell wall that forms between daughter nuclei during cytokinesis in plant cells to separate the cytoplasm

Cell wall

a relatively rigid layer found immediately outside the plasma membrane; in bacteria, archaea, plants, fungi, and some protists; provides support and protection for the cell

Cellular respiration

A process that generates energy-rich molecules called adenosine triphosphate (ATP) from sugars

Central vacuole

membrane-bound organelle in plant cells that functions in storage of water, enzymes, ions, proteins, pigments, and toxins; provides support to plant cell through maintenance of turgor pressure

Centromere

region in a chromosome where the two sister chromatids are tightly associated; point of attachment of spindle microtubules during cell division

Chiasma

site of crossing over between the non-sister chromatids of two homologous chromosomes

Chlorophyll

green pigments located on the thylakoid membranes within chloroplasts which captures light for photosynthesis

Chloroplast

a chlorophyll-containing organelle where photosynthesis occurs; found only in plants and algae (algal protsists)

Chromatid

one of the two identical copies of DNA that make up a replicated chromosome, and are joined at the centromeres; known as sister chromatids

Chromoplast

plastid that contains pigments (carotenoids) giving colouration to flowers and fruits, making them attractive to animals for pollination and seed dispersal

Chromosome

a unit of genetic material composed of DNA and associated proteins, found in the nuclei of eukaryotic cells and in the nucleoid region of prokaryotic cells

Cilium

short, cellular appendages that facilitate locomotion (e.g in Paramecium) or function to sweep fluid over the surface of the cell (e.g epithelial cells from nasal passage where they sweep mucus and debris out of the respiratory tract)

Cleavage furrow

during cytokinesis in animal cells, when a ring of microfilaments contract around the middle of the cell, pinching and tightening until daughter cells are separated

Contractile vacuole

a membrane-bound organelle involved in osmoregulation in animal-like protists (e.g Amoeba and Paramecium)

Crossing over

exchange of segments of the non-sister chromatids of homologous chromosomes when they are in tetrads during prophase 1 of meiosis

Cytokinesis

division of the cytoplasm to form two separate daughter cells

Cytoplasm

fluid region of the cell contained within the plasma membrane containing cytosol, organelles, and cytoskeleton; functions in creating an environment for the processes that take place in the cell (i.e. movement of cell contents, metabolic pathways)

Cytoplasmic bridge

connection between adjacent cells of a colony (e.g Gonium, Eudorina) or multicellular organism (e.g Volvox) that allows communication between cellsC

Cytoplasmic streaming

movement of cytoplasm within a cell; used to circulate cell contents to distribute food and remove wastes, in large algal and plant cells

Cytoskeleton

network of protein filaments in the cytoplasm of a eukaryotic cell; includes microtubules, intermediate filaments, and microfilaments (actin filaments)

Daughter organism

spheres found within Volvox, which are the result of asexual reproduction through mitotic division of reproductive cells

Deoxyribnucleoside triphosphate (dNTP)

building blocks used to produce the copies of DNA during polymerase chain reaction (PCR)

Diffusion

random movement of molecules of a substance from an area of high concentration to an area of low concentration of that substance

Dihybrid cross

experimental mating between two individuals that differ with respect to two characteristics (e.g plant height and seed colour)

Diploid

a cell or organism that has two sets of chromosomes (i.e pairs of homologous chromosomes; 2n)

DNA (deoxyribonucleic acid)

genetic material of an organism; a double-stranded, helical nucleic acid

DNA denaturation

separation of the two strands the DNA double helix; occurs during polymerase chain reaction (PCR)

DNA extraction

performed by chemical lysis of nucleated cells to liberate DNA which is then precipitated out of solution

DNA fingerprint

the unique pattern of migration of restriction of fragments after gel electrophoresis

DNA polymerase

an enzyme that assembles DNA nucleotides into polynucleotides using a pre-existing strand of DNA as a template

DNA synthesis

during the cell cycle, in the S stage, each single chromosome produces an exact copy of itself by DNA synthesis to produce replicated chromosomes

Dominant

an allele that is expressed in both the heterozygous and homozygous conditions 

Duplicated chromosome

chromosome that has two identical sister chromatids, resulting from DNA replication in the S stage of the cell cycle

Egg (ovum, ova)

the non-motile gamete produced by female reproductive organs (archegonia in plants, ovaries in animals)

Embryo

the multicellular stage of a developing organism, following mitotic division of a zygote

Eukaryotic

cell or organism that contains membrane-bound organelles and a true nucleus

Fertilization 

the fusion of haploid gametes (sperm and egg), resulting in a diploid zygote 

Flagellum (flagella)

long cellular appendage specialized for locomotion in some cells (e.g volvocine algae, sperm cells)

Food vacuole

vacuole present in animal-like protists and some cells of multicellular animals; contains food particles engulfed by the cell

Frequency

proportion of one type of individual (genotype or phenotype) to the total population 

G1 phase

first gap phase of the cell cycle when new organelles and proteins are produced and plasma membrane increases in size

G2

second gap phase of the cell cycle

Gamete

a haploid reproductive cell which combines with another gamete during sexual reproduction; egg and sperm

Gametophyte

multicellular haploid generation in the life cycle of a plant that produces gametes (egg and sperm) by mitosis

Gel electrophoresis

technique for separating macromolecules (e.g fragments of DNA) using an electric current and a porous matrix; based on speed of migration of the molecules which is mainly influence by their size

Gene

a unit of hereditary information that contributes to the inherited characteristics or traits of an organism; composed of a specific organized sequence of DNA 

Gene linkage

genes that are located close together (less than 50 map units apart) on the same chromosome and are inherited together

Genetically modified organism (GMO)

an organism with genetic material that has been altered through any artificial process

Genotype

the genetic makeup of an organism (e.g Aa or AaBB)

Glycocalyx

outer covering secreted outside the cell wall by some bacteria; protects cell from adverse conditions (e.g, traps water and protects the cell from desiccation)

Golgi apparatus

organelle made up of flattened, membrane-bound compartments that modify, store, and ship products of the endoplasmic reticulum

Guard cell

in plants, a pair of bean-shaped cells that regulate the opening and closing of stomata

Haploid

a cell or organism which only has one set of chromosomes; n

Heterozygous

individual with two different alleles for the same gene (e.g Aa or Bb)

Homologous chromosomes

chromosomes that have the same size, shape, centromere position and linear sequence of genes; pair up during prophase I to form tetrads

Homozygous

individual with two identical alleles for the same gene (e.g AA or aa)

Hypertonic

when comparing two solutions, this solution has the higher solute concentration

Hypotonic

when comparing two solutions, this solution has the lower solute concentration

Interkinesis

a short, interphase-like stage between Meiosis I and II during which cells can grow but DNA is not replicated

Isotonic

when two solutions have the same solute concentration

Karyotype

photographic representation of the chromosomes of an actively dividing cell, showing the number, shape, and size of the chromosomes

Ladder

a sample of DNA with fragments of known size, used as a reference to estimate the size of other fragments when used in gel electrophoresis

Leucoplast

a type of plastid that lacks pigment; different kinds of these produce and store different macromolecules (starch, protein, or fat)

Locus (loci)

the location of a gene on a chromosome, identified by a labelled line in a chromosome diagram

Lysosome

small, membrane-bound organelle that contains hydrolytic enzymes that digest a cell’s food and wastes

Meiosis I

first division of this process; when homologous chromosomes are separated into two different cells; halves the number of chromosomes (diploid —> haploid)

Meiosis II

second division of this process; when replicated chromosomes are separated into single chromosomes

Mendel’s First Law

alleles of one gene segregate from one another during the formation of gametes 

Mendel’s Second Law

alleles of different genes assort independently of one another during gamete formation

Microfilament

thin type of protein filament that forms part of the cytoskeleton; important in cell strength, shape, and movement; responsible for pseudopodia formation in Amoeba; composed of actin

Microtubule

hollow protein filament that is part of the cytoskeleton; responsible for structure and movement of cilia and flagella, cell organization and shape; composed of tubulin 

Mitochondrion (mitochondria)

double-membrane bound organelle that carriers out cellular respiration and supplies most of cell’s ATP

Mitosis

division of nucleus to produce two genetically identical daughter nuclei, each with the same complement of chromosomes

Monohybrid cross

a cross between two individuals that differ in respect to one characteristic (e.g plant height)

Normal distribution

a set of continuous data for which the mean is the most common value, with a symmetrical decrease in frequency for values above and below the mean, forming a bell-shaped curve

Nuclear envelope

double membrane, perforated with pores, that surrounds the nucleus

Nucleoid region

region of prokaryotic cell where genetic material is located

Nucleolus (nucleoli)

prominent region in nucleus of nondividing cells where ribosome subunit assembly occurs

Nucleus (nuclei)

membrane-bound organelle containing most of the cell’s genetic material; controls cell function (by directing protein synthesis); site of DNA synthesis and RNA transcription

Osmoregulation

control of water and ion balance within a cell or organism

Osmosis

movement of solvent (usually water) through a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration

Ovary (ovaries)

in animals, the female reproductive organ which produces eggs/ova

Parental gametes

in a test cross, the gametes that come from the parents of the heterozygous organism, i.e., those that are not the result of recombination/crossing over and are produced more frequently 

Passive transport

The movement of substances across a plasma membrane without requiring energy

Pedigree charts

diagram that shows the occurrence of phenotypic traits or genetic diseases in successive generations, usually in humans; enable the analysis of how these traits are passed from parents to offspring

Phagocytosis

cellular process that involves engulfing food particles into the cell’s cytoplasm (seen in Amoeba)

Phenotype

physical characteristics of an organism that are the result of its expressed genes