Unit 2 - Genetics Flashcards
heredity
the passing of traits from parents to offspring
genetics
the branch of biology dealing with heredity and the variation of inherited characteristics
deoxyribonucleic acid (DNA)
a molocule that carries genetic information in cells
gene
a segment of a DNA molecule that codes for a particular trait; found at a specific location on a chromosome
locus
the location of a gene on a chromosome
polyploid
having more that two sets of chromosomes; many plants are plyploids
asexual reproduction
the production of offspring from a single parent; the genetic makeup of the offspring is identical to that of the parent
sexual reproduction
the production of offspring from the fusion of two sex cells (usually from two different parents); the genetic makeup of the offspring is different from that of either parent
fragmentation
a method of asexual reproduction in which a piece or body fragment of the parent organism develops into a mature individual
mitosis
the process by which a eukaryotic cell divides the genetic material in its nucleus into two new identical nuclei
interphase
the portion of the cell cycle between mitotic divisions when the genetic material is duplicated
chromatin
the tangled strands of DNA and protein within a eukaryotic nucleus
sister chromatid
the identical copy of a single chromosome that remains attached to the original chromosome at the centromere
cytokinesis
the process in which a eukaryotic cell divides its cytoplasm into two new daughter cells
cloning
the process of producing one individual that is genetically identical to another, using a single cell or tissue
biotechnology
the use and modification of organisms for applications in engineering, industry, and medicine
genetically modified organism
an organism in which the genetic material has been altered using genetic engineering techniques
gamete
a sex cell; includes sperm cells in males and egg cells in females
fertilization
the formation of a zygote by the joining together, or fusion, of two gametes
zygote
a cell produced by the fusion of two gametes
meiosis
a two-stage cell division in which the resulting daughter cells have half the number of chromosomes as the parent cell; results in the formation of gametes or spores
homologous chromosomes
matching pairs of chromosomes, similar in size and carrying information for the same genes
tetrad
a pair of homologous chromosomes, each with two sister chromatids
synapsis
the physical pairing up of homologous chromosomes during prophase I of meiosis
crossing over
the exchange of chromosome segments between homologous pairs during synapsis
gametogenesis
the production of gametes (sex cells) in animals
spermatogenesis
the production of mature sperm cells
oogenesis
the production of mature egg cells
karyotype
the chromosomes of an individual that have been sorted and arranged according to size and type
sex chromosomes
chromosomes that differ in males and females of the same species; the combination of sec chromosomes determines the sex of the offspring
autosomes
non-sex chromosomes
non - disjunction
the failure of homologous chromosomes to move to opposite poles of the cell during meiosis; results in an abnormal number of chromosomes in the daughter cells
trisomy
a chromosomal abnormality in which there are three homologous chromosomes in place of a homologous pair
monosomy
a chromosomal abnormality in which there is a single chromosome in place of a homologous pair
down syndrome
a chromosomal abnormality in which an individual has three copies of chromosome number 21; also referred to as trisomy 21
prenatal testing
testing for a genetic disorder that occurs prior to birth
maternal inheritance
a type of inheritance in which a sygote formed from two gametes inherits cytoplasmic DNA from only the female gamete
trait
particular version of a characteristic that is inherited, such as hair colour or blood type
hyrbid
the offspring of two different true-breeding plants
cross
the successful mating of two organiss from distinct genetic lines
law of segregation
the scientific law stating that 1) organisms inherit two copies of genes, one from each parent, and 2) organisms donate only one copy of each gene to their gametes because the genes separate during gamete formation
allele
a specific form of a gene
homozygous
an individual that carries two of the same alleles for a given characteristic
heterozygous
an individual that carries two different alleles for a given characteristic
genotype
the genetic makeup of an individual
phenotype
an individual’s outward appearance with respect to a specific characteristic
dominant allele
the allele that, if present, is always expressed
recessive allele
the allele that is expressed only if it is not in the presence of the dominant allele, that is, if the individual is homozygous for the recessive allele
test cross
used to determine the genotype of an individual expressing a dominant trait
complete dominance
a situation where an allele will determine the phenotype, regardless of the presence of another allele
incomplete dominance
a situation where neither allele dominates the other and both have an influence on the individual (results in partial expression of both traits - blends)
codominance
a situation where both alleles are expressed fully to produce offspring with a third phenotype
pedigree
a diagram of an individual’s ancestors used in human genetics to analyze the Mendelian inheritance of a certain trait; also used for selective breeding of plants and animals
autosomal inheritence
inheritence of alleles located on autosomal (non-sex) chromsomes
of chormosomes in humans
46
of PAIRS of chromosomes in humans
23
sex-linked
describes an allele that is found on one of the sex chromosomes (X or Y) and when passed on to offspring is expressed
X-linked
phenotypic expression of an allele that is found on the X chromosomes
Y-linked
phenotypic expression of an allele that is found on the Y chromosome
mutation
a change in the genetic code of an allele; the change may have a positive effect, a negative effect, or no effect
carrier testing
a genetic test that determines whether an individual is heterozygous for a given gene that results in a genetic disorder
genetic screening
tests used to identify the presence of a defective allele that leads to a genetic disorder
phenylketonuria (PKU)
an autosomal, recessive, inherited genetic disorder that results in the accumulation of phenylalanine in the tissues and blood
cystic fibrosis
causes the body to produce thick, sticky mucus that clogs the lungs and pancreatic duct
hemophilia
recessive allele that causes the body to be unable to form blood clots
Huntington’s disease
dominant allele that causes progressive, irreversible degeneration of the nervous system
dihybrid cross
a cross that involves two genes, each consisting of heterozygous alleles
law of independent assortment
if genes are located on separate chromosomes, they will be inherited independently of one another
which abbot conducted extensive experiments mainly with pea plants in the 19th century, which led to our current understanding of genetics, and is known as “the father of genetics”?
Gregor Mendel
