7- Heredity ✅ Flashcards
Autosomes
The chromosomes that are not linked to sex
Centromere
The centre connecting point in-between two chromotids
Chromosome
The structure composed of DNA and protein that contains along its length linear arrays of genes carrying genetic information.
Chromatid
The daughter strands of a duplicated chromosome joined together by the centromere
Chromatin
A complex of proteins and DNA in eukaryotic cells
Diploid (2n)
Two sets of matching homologous chromosomes
Gametes
Sex cells, also known as gametocytes
Gene
The basis of heredity; segment of DNA that codes for the formation of a polypeptide
Genome
All of the genetic material contained within an organism or a cell; includes both the chromosomes within the neurone and the DNA of the mitochondria
Haploid (n)
One set of chromosomes
Heredity
The study of inheritance
Heterosomes
Non-identical chromosomes pairing up at meiosis. (X&Y in males)
Histones
A type of protein associated with DNA in eukaryotic cells
Homologous chromosomes
Pairs of chromosomes that have the same: size snap, and genes at the same location
Karyotype
The display of the number, size, and shape of chromosomes
Sex chromosomes
Chromosomes that affect sexual traits; one has homologous sex chromosomes the other has a dissimilar.
Somatic cells
Normal body cells as compared with germ-line cells from which the gametes are derived
Anaphase
A stage in cell division in which the chromosomes move to the poles of the new cells
Binary fission
Division of a cell into two without mitosis; a prokaryotic cell splits to form two daughter cells
Cytokinesis
Division of the cytoplasm
DNA helicase
An enzyme that helps the two strands of the DNA double helix unwind and separate
DNA ligase
An enzyme used to catalyse the formation of a bond between two pieces of DNA
DNA polymerase
An enzyme capable of making an exact copies of fragments of DNA
G1 phase
The stage begins with dismantling of the structures that remain in the cell from from the previous cell division. The cell grows in size and metabolises important enzymes that are required for DNA synthesis.
G2 phase
The cell prepares it self for mitosis during this stage, synthesising the mitotic spindle and preparing for the condensation of the chromosomes.
Interphase
The stage in between nuclear division where the cell performs its everyday function.
Meiosis
A two phase type of cellular division in which the chromosome number of cell is halved to haploid a number; meiosis is the basis of gamete formation in animals and spore formation in plants
Metaphase
A stage in cell division processes of meiosis and mitosis. During this stage the chromosomes line up at the equatorial plane of the cell.
Mitosis
A process of nuclear division that maintains the parental number of chromosomes for daughter cells; it is the basis of bodily growth and asexual reproduction in many eukaryotic cells.
Prophase
The first stage in the cell division process of meiosis and mitosis. Chromatin threads condense and sister chromatids become visible (held together by a centromere) a spindle forms and the nucleolus disappears, as the nuclear envelope breaks down.
Replication fork
The site of the split in the DNA double helix as caused by DNA helicase.
S phase
DNA synthesis occurs at this stage. The centrioles separate and replicate.
Semiconservative replication
The production of two new DNA double helix molecules, each consisting of one parental strand and one daughter strand.
Synapsis
The pairing of homologous chromosomes
Telophase
The late stage of mitosis or meiosis. In this the chromosomes regain their original form and the spindle fibres degenerate and the nuclear envelope reforms in each daughter cell.
Zygote
First cell of a new individual, which is formed by fusion of a sperm and an ovum at fertilisation.
Alleles
Alternative form of a gene
Carrier
An individual who is heterozygous for a recessive gene
Dominant trait/characteristic
The trait that when paired with another will be present phenotypically
Genotype
The collection of genes or gene profile of an individual; the range of alleles that organism processes
Heterozygous
The genotype where the pair of alleles are different
Homozygous
The genotype where the two alleles are both the same
Linkage group
A group of genes known to be associated on a chromosome
Linked genes
The tendency of two or more genes known to be inherited together during meiosis
Locus
The position a gene occupies on an organism
Phenotype
The observable traits of an organism that arise because of interaction between genes and the environment
Pure breeding
Organisms that are homozygous for on or more loci and express that same phenotype of the genes over many generations unless a mutation occurs
Recessive trait/characteristic
The trait that when paired with another is not easily seen
Chiasma
The point where homologous chromosomes are joined in prophase 1 of meiosis
Codominance
The quality of two heterozygous alleles that are fully expressed in the phenotype.
Crossing over
parts of homologous chromosomes are exchanged, occurs at the Chiasma
Dihybrid crosses
A cross of two individuals that are heterozygous at two loci
Dominance hierarchy
Unknown
First filial (F1) generation
The offspring of the parental generation
Hemizygous
Unknown
Independent assortment of alleles
Each alleles of one gene may combine independently with each of the alleles of another gene in a gamete
Lethal gene
A alleles pair, that when combined causes death of the organism
Monohybrid cross
A cross between organisms that involves only a single gene, usually with two different alleles.
Multiple alleles
When three or more alleles of a gene exist among members of a population
Punnet square
A visual representation in the form of a table of the possible genotypes and therefore phenotypes that can result from the random fusion of gametes for either one or two traits.
Reciprocal cross
A cross made between two organisms to determine the pattern of inheritance or a certain characteristic.
Recombinant chromosomes
Usually refers to chromosomes that have been deliberately manipulated in laboratories by isolating, cutting and recombining as a means of altering its structure and function.
Second filial (F2) generation
The grandchildren of the parental generation/the children of the children, who are the children to the parental generation
Sex linked genes
Genes that are carried on a sex chromosome
Test cross
In genetics, a deliberate cross between two organisms to determine whether one of the individuals is heterozygous or homozygous dominant for a particular trait.
X linked genes
Genes that are present on the X chromosome
Asexual reproduction
Reproduction form a single parent without the production of gametes
Continuous variation
Variation of a characteristic in a population that is controlled by a number of genes, that is, shows multifunctional inheritance.
Discontinuous variation
Variation of a characteristic in a population that is controlled by a single gene, that is, shows single (either/or) factor inheritance
Pedigree chart
A graphic representation of a pedigree
Polygenetic trait
A trait that is coded for by multiple loci which cumulatively impact the phenotypic expression.
Autosomal dominant
Two affected parents may have an unaffected child
May be heterozygous or homozygous
Does not skip generations
Autosomal recessive
Two unaffected parents may have an affected child
Can skip a generation
Only homozygous
Sex-linked dominant
An affected father will pass it to daughters, but non of his sons.
More females will have he condition than males
Does not skip a generation.
Sex-linked recessive
A mother will pass it to all of her sons but none of her daughters
Heterozygous females are called carriers
More males will have it than females
May skip a generation
Bivalent
Visible bodies in a cell during prophase one of meiosis, which are made up of two homologous chromosomes joined together.
Cancer
Mass of cells that divide uncontrollably
Cell cycle
The sequence of events from one flee division to another
Centrioles
Minute rod shaped bodies present in many resting cells jobs outside the nuclear membrane; these structures double before mitosis, moving apart from the poles of the spindle; they are usually absent in plants.
Cleavage
Division of the cytoplasm in an animal cell
Cleavage furrow
A shallow, ring like depression that forms at the cell surface of an animal cell undergoing cytokinesis as contractile microfilaments pull the plasma membrane inward; it defines where the cytoplasm will be cut in two.
Disjunction
Moving apart of homologous chromosomes during anaphase of meiosis
Plasmid
A small circular bit of DNA found in bacteria and which is able to replicate independently of the cells’ chromosomes; they can carry antibiotic resistance
