Definitions Flashcards
Cell
The basic unit of structure and function for all living organisms
Tissue
Multicellular organisms, similar cells, combine to form a tissue.
Organ
A group of tissues combine to form organs for a specific function
Organ system
A group of organs working together as a whole for a specific function
Organism
A complete living thing
Population
Organisms of the same species in a particular area
Community
Interacting populations in a particular area
Ecosystem
A community plus the physical environment
Biosphere
Regions of the earth’s crust, waters, and atmosphere inhabited by living things. The entire world!
Hypothesis
An educated guess
Theory
Concepts that join together well-supported and related hypotheses
Proton
Positive particle:: In the nucleus of an atom
Electron
Negatively charge particle:: In the nucleus of an atom
Neutron
Uncharged particle :: move in orbitals AROUND the nucleus in an electron shell.
Molecule
Electrically neutral group of two or more atoms held together by chemical bonds
Compound
Pure chemical substance consisting of two or more chemical substances that can be combined into smaller substances to create chemical bonds
Atomic number
Number of protons in an atom
Mass number
The sum of protons and neutrons in the nucleus
Acid
releasing hydrogen (H+) ions
Bases
take up hydrogen ions
Polymer
Largest of the biomolecules
Monomers
Subunits of polymer
Examples: amino acids (monomers) are linked to form a protein (polymer);
Example: many nucleotides (monomers) are linked to form a nucleic acid (polymer).
Peptide bond
synthesized when the carboxyl group of one amino acid molecule reacts with the amino group of the other amino acid molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis reaction
Cytoskeleton
a network of fibers composed of proteins contained within a cell’s cytoplasm.
Ex: actin filaments, intermediate filaments, and microtubules
Turgor pressure
Swelling of a plant cell in hypotonic solution
Helps plant maintain erect position.
Crenation
Red blood cells that have shrunk
Plasmolysis
Shrinking of the cytoplasm due to osmosis
Active site
a small port in an enzyme where substrate molecules bind and undergo a chemical reaction.
Induced fit model
only the proper substrate is capable of inducing the proper alignment of the active site that will enable the enzyme to perform its catalytic function
Thylakoid
is a membrane-bound compartment inside chloroplasts and cyanobacteria
Stroma
Supportive framework of an organ
Photosystem
Pigment complex (Chl A, Chl B & Carotenoids) and electron acceptor molecules within the thylakoid membrane
Chlorophyll a
used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light.
Chlorophyll b
accessory pigment and acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a.
Photolysis
chemical process by which molecules are broken down into smaller units through the absorption of light
Deamination
removal of an amine group from a molecule.
AMMONIA produced by deamination of AMINO acids.
Nucleotide
Structural components or building blocks of DNA
Nitrogenous base-pairing
Helicase
an enzyme that unwinds and separates the two strands of the DNA double helix.
DNA polymerase
enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA.
Ribosome
Site in a molecule that synthesizes protein
Codon
a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
Anticodon
a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA.
Promotor
A promoter is a region of DNA which defines the start of the gene, the direction of transcription, and the strand to be transcribed.
Start codon
site at which translation into protein sequence starts
Stop codon
site at which translation into protein sequence stops
G1
first growth period of the cell cycle
S
DNA synthesizes
Haploid
number of chromosomes in a gamete
Diploid
two complete sets of chromosomes. ALL SOMATIC CELLS
Inversion
occur when a chromosome breaks in two places and the resulting piece of DNA is reversed and re-inserted into the chromosome
Deletion
loss or absence of a section from a nucleic acid molecule or chromosome
Duplication
a DNA segment in a chromosome that is a copy of another segment
Translocation
chromosome alteration in which a whole chromosome or segment of a chromosome becomes attached to or interchanged with another whole chromosome
Gamete
Sperm or Egg
Zygote
initial cell formed when two gamete cells are joined by means of sexual reproduction. FETUS
Plasmids
a small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently. BACTERIA
Vector
an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another
Gel electrophoresis
a method for separation and analysis of macromolecules and their fragments, based on their size and charge.
Used in DNA sequencing
Incomplete dominance
form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele
Codominance
a relationship between two versions of a gene
Pleiotropy
occurs when one gene influences multiple, seemingly unrelated phenotypic traits, an example being phenylketonuria
Multiple Alleles
a type of non-Mendelian inheritance pattern that involves more than just the typical two alleles that usually code for a certain characteristic
Polygenic inheritance
occurs when one characteristic is controlled by two or more genes
Dominate allele
produces a dominant phenotype in individuals who have one copy of the allele
Recessive allele
An allele whose phenotypic effect is not expressed in a heterozygote
Homozygous
having identical pairs of genes for any given pair of hereditary characteristics
Heterozygous
having dissimilar pairs of genes for any hereditary characteristic
Genotype
genetic makeup of a cell, an organism, or an individual usually with reference to a specific characteristic under consideration
Phenotype
composite of an organism’s observable characteristics or traits
Epistasis
phenomenon that consists of the effect of one gene being dependent on the presence of one or more ‘modifier genes’
Homologous structure
an example of an organ or bone that appears in different animals
Analogous Structure
similarity of function and superficial resemblance of structures that have different origins
Vestigial structure
organs that performed some important function in the organism at one point in the past.
Human Example: Appendix
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