genetics exam 4

nucleosomes

composed of DNA and chromosomes proteins (histones)

histones

chromosomal proteins

scaffold

central core of the chromosomes

heterochromatin

deeply staining with chromosome stains, more densely packed, few active genes, typically surrounds centromeres

euchromatin

lightly staining with chromosome stain, less densely packed, most active genes, near ends of chromosome

centromere

links a pair of sister chromatids together during cell division

DNA ligase

enzyme that seals together fragments of DNA

plasmid

replicating fragments of DNA separate from main bacterial chromosome. restriction fragment can be amplified in them

ethidium bromide

used to stain gel; fits between stacked bases in DNA. when it is in DNA, it gives off visible light in the presence of ultraviolet light

restriction fragment

a DNA fragment resulting from the cutting of a DNA strand by a restriction enzyme, a process called restriction

restriction map

the recognition sites for restriction endonuclease can be ordered on a piece of DNA

dideoxynucleotide

chain-elongating inhibitors of DNA polymerase, used in the Sanger method for DNA sequencing

telomere

structures made from DNA sequences and proteins found at the ends of chromosomes

variable number tandem repeats

Locations in a genome where a short sequence of nucleotides is repeated adjacent to each other

SINEs

short repetitive, non-coding sequences ranging in size from 100–600 bp

LINEs

an exchange between

telocentric

centromere near the end of the chromosomes

acrocentric

centromere off-center

metacentric

centromere near middle

acentric

lacking a centromere

holocentric

chromosomes that possess multiple kinetochores along their length rather than the single centromere typical of other chromosomes

deletion

A type of genetic change that involves the absence of a segment of DNA - a piece is missing

duplication

two copies of the same piece

inversion

A chromosomal defect in which a segment of the chromosome breaks off and reattaches in the reverse direction — a piece turned around

translocation

an exchange between non-homologous chromosomes

inversion loop

when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm.

paracentric inversion

one in which a paracentric portion of a chromosome has been rotated through 180° and re-inserted in the same location

dicentric bridge

During mitosis, the spindles can attach to both centromeres and the dicentric chromosome can be pulled in opposite directions forming an anaphase/chromatin 'bridge'

acentric fragment

a segment of a chromosome that lacks a centromere

alternate segregation

when alternate centromeres go to the same pole — all the genetic material is still present in all gametes

adjacent 1 segregation

segregation of non-homologous centromeres during meiosis in a reciprocal translocation heterozygote such that unbalanced gametes with duplications and deficiencies are produced.

adjacent 2 segregation

leads to the formation of gametes containing chromosomes 1 and 2, and 3 and 4

euploid

an embryo with the correct number of 46 chromosomes. In other words, this is a “normal” embryo.

aneuploid

The occurrence of one or more extra or missing chromosomes in a cell or organism

monosomic

the condition in which only one chromosome from a pair is present in cells rather than the two copies usually found in diploid cells

trisomic

a genetic condition that results in an extra copy of a chromosome

double trisomic

gain of two chromosomes or gain/loss of at least two chromosomes

nondisjunction

the failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes.

monoploid

An individual that contains one half the normal number of chromosomes

polyploid

the heritable condition of possessing more than two complete sets of chromosomes

haploid

the presence of a single set of chromosomes in an organism's cells.

colchicine

used to develop polyploid plants and functions as a mitotic poison by producing many mutagenic effects on plants

autopolyploid

an individual that possesses more than two sets of chromosomes arising from a single parental species

allopolyploid

a species that has more than two sets of chromosomes that originate from different species.

homologous

a gene inherited in two species from a common ancestor

triploidy

a rare genetic condition that causes a developing fetus to have 69 total chromosomes in their cells instead of 46 total

quadrivalent

composed of four homologous chromosomes synapsed in meiotic prophase

trivalent

a chromosome formed by three homologous chromosomes that lie close together or appear to join completely during meiosis

univalent

A chromosome that fails to pair with another during the prophase stage of meiosis, and therefore does not exchange genetic information via crossing over.

bivalent

a set of two chromosomes wherein one of the chromosomes comes from the maternal homologue inherited from the female gamete while the other chromosome is from the paternal homologue inherited from the male gamete

nullisomic

a genetic condition involving the lack of both the normal chromosomal pairs for a species (2n-2)

extranuclear genes

the transmission of genes occuring outside the nucleus.

cytoplasmic genes

the inheritance of organelle DNA from the parents

plastids

photosynthetic organelles of algae and plants

cytoplasmic segregation

specifies polarity of the zygote, i.e. which end is 'top' and which is 'bottom', and this fundamentally influences future embryonic development

maternal effect

genes are expressed during oogenesis by the mother (expressed prior to fertilization) and develop the anterior-posterior and dorsal ventral polarity of the egg

electrophoresis

a laboratory technique used to separate DNA, RNA or protein molecules based on their size and electrical charge

polymerase chain reaction

a nucleic acid amplification testing procedure that consists of denaturing, renaturing, elongating, and amplifying a short segment of DNA or RNA.

CENH3

Centromere-specific histone H3 (CENH3) has been used to detect active centromeres, and to analyse the DNA sequences closely associated with the centromere, because they localize only in active centromeres and bind directly to the DNA.

restriction fragment length polymorphism (RFLP)

a restriction enzyme will cut genomic DNA into many fragments

if one considers a single fragment, it will be a certain length

that length depends upon the distance between two recognition sequences

What is the role of restriction endonucleases, DNA ligase, and cloning vectors in generating recombinant DNA?

restriction enzymes recognize and cut specific target sequences in DNA molecules, creating compatible sticky ends for joining target DNA and vector DNA

How are staggered cuts that are made by restriction enzymes particularly useful for generating recombinant DNA?

Staggered cuts made by restriction enzymes are particularly useful for generating recombinant DNA because they create "sticky ends" that facilitate the joining of different DNA fragments

How are restriction fragments analyzed using gel electrophoresis?

Restriction fragments are analyzed using gel electrophoresis by loading DNA samples mixed with a loading dye into an agarose gel. An electric current is applied, causing the negatively charged DNA to migrate toward the positive electrode, with smaller fragments traveling further than larger ones. After running the gel, it is stained with a DNA-binding dye for visualization under UV light. By comparing the bands to a DNA ladder of known sizes, researchers can determine the sizes of the fragments and analyze genetic information.

What are the necessary characteristics of a plasmid cloning vector?

A plasmid cloning vector should have an origin of replication for independent replication, a selectable marker (like an antibiotic resistance gene) for identifying successful transformations, and a multiple cloning site (MCS) for easy insertion of foreign DNA. Additionally, it may include a promoter region for gene expression, must be stable to minimize gene loss, should be of a manageable size, and needs to be compatible with the host organism for efficient uptake and replication.

adjacent-1 segregation

when adjacent centromeres go together — creates duplications and deficiencies, which are usually inviable

adjacent-2 segregation

occurs when homologous centromeres go to the same pole. this is rare