Genetics
study of heredity, how inherited variation is encoded, replicated, and expressed, and how it evolves over time
Genomes
-the complete set of genetic instructions for any organism -all of these are encoded in nucleic acids (either DNA or RNA)
transmission genetics (classical genetics)
encompasses the basic principles of heredity and how traits are passed from one generation to the next
transmission genetics examples
relation between chromosomes and heredity, the arrangement of genes on chromosomes, and gene mapping
molecular genetics
chemical nature of the gene itself: how genetic information is encoded, replicated, and expressed
molecular genetics examples
cellular process of replication, transcription, and translation (by which genetic info is transferred from one molecule to another) and gene regulation (the processes that control the expression of genetic info)
population genetics
explores the genetic composition of populations (groups of individuals of the same species) and how that composition changes geographically and with the passage of time
population genetics examples
evolution
model genetic organism
organisms that are widely used in genetic research and that can serve as models for the genetic systems of other organisms
pangenesis
(incorrect) genetic info travels from different parts of the body to reproductive organisms
Inheritance of Aquired Characteristics (Lamarck)
(incorrect) acquired traits become incorporated into hereditary information.
Preformationism
(incorrect) minuture organism resides in sex cells and all traits are inherited from one parent
blending inheritance
-incorrect -genes blend and mix
germ-plasm theory
(correct) all cells contain a complete set of genetic information
cell theory
(correct) all life is composed of cells, and cells arise only from cells
Mendelian inheritance
correct; traits are inherited in accord with defined principles
gene
is the fundamental unit of heredity
Phenotypes are
physical expressions of genetic traits Ex. eye color
Chromosomes
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Mutations
Random errors in gene replication that lead to a change in the sequence of nucleotides. The source of all genetic diversity.
Evolution
Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.
Prokaryote
A unicellular organism that lacks a nucleus and membrane bound organelles
Eukaryotes
compartmentalized cell structure with components bounded by intercellular membranes(may be either unicellular or multicellular)
Nucleus
a nuclear membrane surround this, stores the genetic material
Histones
form tightly packed chromosomes (special class of stuff of eukaryotic chromosomes
Virusis
Smallest microorganisms known to cause infectious diseases
3 fundamental events cells have to do to reproduce successfully
its genetic information must be copied
the copies must be separated from each other
the cell must divide
binary fission
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size
homologous pair
a pair of chromosomes, one from each parent, that have relatively similar structures and gene values
dipoid
(2n) a cell containing two sets of chromosomes inherited by each parent
Haploid
(genetics) an organism or cell having only one complete set of chromosomes
Polyploid
having three or more of each type of chromosome characteristic of the species
Centromere
Constricted region in a eukaryotic chromosome where sister chromatids are attached
Telomeres
stable ends of linear chromosomes
origin of replication
sites where DNA synthesis begins, unlike centromeres and telomeres, they are not easily observed by microscopy
sister chromatids
2 identical copies of the same chromosome that are held together at the centromere
condensins
bind to the DNA within chromosomes and bring about condensation, are a type of structural maintenance of chromosomes complex, also plays a role in chromosome segregation in bacteria
G0 phase
stable, non dividing period of variable length
Interphase
G1 phase, S phase, G2 phase
G1 phase
growth and development of the cell; G1/S checkpoint
S phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
G2 phase
preparation for division; G2/M checkpoint
M phase
prophase, metaphase, anaphase, telophase
Prophase
chromosomes condense and mitotic spindle forms
Prometaphase
nuclear membrane disintegrates and spindle microtubules anchor to kinetochores.
Anaphase
sister chromatids separate, becoming individual chromosomes that migrate toward spindle poles
Metaphase
chromosomes align on the metaphase plate; spindle - assembly checkpoint
Telophase
chromosomes arrive at spindle poles, the nuclear membrane re-forms and the condensed chromosomes relax
Cytokinesis
the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.
crossing over
takes place in prophase 1, refers to the exchange of genetic material between non-sister chromatids (chromatids from different homologous chromosomes
Recombination
the creation of new combinations of alleles on a chromatid
Prophase 1
Chromosomes condense, homologous chromosomes synapse, crossing over takes place, nuclear envelope breaks down, and mitotic spindle forms.
Metaphase 1
homologous chromosomes line up in the middle of the cell
Anaphase 1
the two chromosomes (each with two chromatids) of a homologous pair separate and move toward opposite poles
Telophase 1
chromosomes arrive at the spindle poles
prophase 2
chromosomes condense, the spindle forms, and the nuclear membrane disintegrates
metaphase 2
individual chromosomes line up on the metaphase plate
Anaphase 2
sister chromatids separate and move as individual chromosomes toward opposite spindle poles
telophase 2
the chromosomes arrive at opposite poles
nuclei form around each set and the chromosomes unwind -the spindle breaks down and a nuclear envelope re-forms
cohesion
a protein that holds chromatids together, is key to the behavior of chromosomes in mitosis and meiosis
Spermatogenesis
Formation of sperm
spermatogonia
a cell produced at an early stage in the formation of spermatozoa, formed in the wall of a seminiferous tubule and giving rise by mitosis to spermatocytes.
spermatids
four haploid cells that are formed when a diploid reproductive cell divides meiotically
Oogenesis
the production, growth, and maturation of an egg, or ovum
1st polar body
the cell may or may not divide further
second polar body
a small body containing the chromosomes discarded during the second meiotic division of an ovum
super coiling of DNA
takes place when the DNA helix is subjected to strain by being overwound or under wound
relaxed state
a stretch of 100 bp of DNA would assume about 10 complete turns
positive super coiling
molecules that are over rotated exhibit this
negative super coiling
under rotated molecules exhibit this
topoisomerase
corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining DNA strands
Nucleoid
confined to a definite region of the cystoplasm, its DNA frequently appears as a distinct clump
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
Euchromatin
undergoes the normal process of condensation and de-condensation in the cell cycle
Heterochromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.
nonhistone chromosomal proteins
chromatin constituents other than histones with a wide variety of functions. Human chromosomes associate with several thousand different kinds of nonhistone proteins.
Nucleosome
repeating subunit of chromatin fibers, consisting of DNA coiled around histones
topologically associated domains (TADs)
Large regions of spatially interacting chromatin; help to control gene expression in eukaryotic cells.
polytene chromosomes
Giant chromosomes
arise when repeated rounds of DNA replication take place without accompanying cell divisions, producing thousands of copies of DNA that lie side by side
chromosome puffs
Localized swelling of a polytene chromosome; a region of chromatin in which DNA has unwound and is undergoing transcription.
epigenetic changes
Changes to the chemical groups that associate with DNA that are transmitted to daughter cells after cell division
telomeric sequences
usually consist of repeated units of a series of adenine or thymine nucleotides followed by several guanine nucleotides, taking the forms 5'-(A and T)m Gn-3' where m ranges from1-4 and n is 2 or more
Shelterin
A multiprotein complex that binds to mammalian telomeres and protects the ends of the DNA from being inadvertently repaired as a double-stranded break in the DNA.
C-value
the total amount of DNA in the haploid genome of a species
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