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Flashcards in 7- Heredity ✅ Deck (83):
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Autosomes

The chromosomes that are not linked to sex

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Centromere

The centre connecting point in-between two chromotids

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Chromosome

The structure composed of DNA and protein that contains along its length linear arrays of genes carrying genetic information.

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Chromatid

The daughter strands of a duplicated chromosome joined together by the centromere

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Chromatin

A complex of proteins and DNA in eukaryotic cells

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Diploid (2n)

Two sets of matching homologous chromosomes

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Gametes

Sex cells, also known as gametocytes

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Gene

The basis of heredity; segment of DNA that codes for the formation of a polypeptide

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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

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Haploid (n)

One set of chromosomes

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Heredity

The study of inheritance

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Heterosomes

Non-identical chromosomes pairing up at meiosis. (X&Y in males)

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Histones

A type of protein associated with DNA in eukaryotic cells

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Homologous chromosomes

Pairs of chromosomes that have the same: size snap, and genes at the same location

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Karyotype

The display of the number, size, and shape of chromosomes

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Sex chromosomes

Chromosomes that affect sexual traits; one has homologous sex chromosomes the other has a dissimilar.

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Somatic cells

Normal body cells as compared with germ-line cells from which the gametes are derived

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Anaphase

A stage in cell division in which the chromosomes move to the poles of the new cells

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Binary fission

Division of a cell into two without mitosis; a prokaryotic cell splits to form two daughter cells

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Cytokinesis

Division of the cytoplasm

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DNA helicase

An enzyme that helps the two strands of the DNA double helix unwind and separate

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DNA ligase

An enzyme used to catalyse the formation of a bond between two pieces of DNA

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DNA polymerase

An enzyme capable of making an exact copies of fragments of DNA

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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.

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G2 phase

The cell prepares it self for mitosis during this stage, synthesising the mitotic spindle and preparing for the condensation of the chromosomes.

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Interphase

The stage in between nuclear division where the cell performs its everyday function.

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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

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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.

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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.

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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.

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Replication fork

The site of the split in the DNA double helix as caused by DNA helicase.

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S phase

DNA synthesis occurs at this stage. The centrioles separate and replicate.

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Semiconservative replication

The production of two new DNA double helix molecules, each consisting of one parental strand and one daughter strand.

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Synapsis

The pairing of homologous chromosomes

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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.

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Zygote

First cell of a new individual, which is formed by fusion of a sperm and an ovum at fertilisation.

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Alleles

Alternative form of a gene

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Carrier

An individual who is heterozygous for a recessive gene

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Dominant trait/characteristic

The trait that when paired with another will be present phenotypically

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Genotype

The collection of genes or gene profile of an individual; the range of alleles that organism processes

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Heterozygous

The genotype where the pair of alleles are different

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Homozygous

The genotype where the two alleles are both the same

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Linkage group

A group of genes known to be associated on a chromosome

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Linked genes

The tendency of two or more genes known to be inherited together during meiosis

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Locus

The position a gene occupies on an organism

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Phenotype

The observable traits of an organism that arise because of interaction between genes and the environment

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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

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Recessive trait/characteristic

The trait that when paired with another is not easily seen

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Chiasma

The point where homologous chromosomes are joined in prophase 1 of meiosis

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Codominance

The quality of two heterozygous alleles that are fully expressed in the phenotype.

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Crossing over

parts of homologous chromosomes are exchanged, occurs at the Chiasma

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Dihybrid crosses

A cross of two individuals that are heterozygous at two loci

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Dominance hierarchy

Unknown

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First filial (F1) generation

The offspring of the parental generation

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Hemizygous

Unknown

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Independent assortment of alleles

Each alleles of one gene may combine independently with each of the alleles of another gene in a gamete

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Lethal gene

A alleles pair, that when combined causes death of the organism

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Monohybrid cross

A cross between organisms that involves only a single gene, usually with two different alleles.

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Multiple alleles

When three or more alleles of a gene exist among members of a population

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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.

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Reciprocal cross

A cross made between two organisms to determine the pattern of inheritance or a certain characteristic.

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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.

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Second filial (F2) generation

The grandchildren of the parental generation/the children of the children, who are the children to the parental generation

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Sex linked genes

Genes that are carried on a sex chromosome

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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.

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X linked genes

Genes that are present on the X chromosome

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Asexual reproduction

Reproduction form a single parent without the production of gametes

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Continuous variation

Variation of a characteristic in a population that is controlled by a number of genes, that is, shows multifunctional inheritance.

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Discontinuous variation

Variation of a characteristic in a population that is controlled by a single gene, that is, shows single (either/or) factor inheritance

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Pedigree chart

A graphic representation of a pedigree

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Polygenetic trait

A trait that is coded for by multiple loci which cumulatively impact the phenotypic expression.

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Autosomal dominant

Two affected parents may have an unaffected child
May be heterozygous or homozygous
Does not skip generations

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Autosomal recessive

Two unaffected parents may have an affected child
Can skip a generation
Only homozygous

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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.

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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

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Bivalent

Visible bodies in a cell during prophase one of meiosis, which are made up of two homologous chromosomes joined together.

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Cancer

Mass of cells that divide uncontrollably

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Cell cycle

The sequence of events from one flee division to another

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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.

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Cleavage

Division of the cytoplasm in an animal cell

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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.

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Disjunction

Moving apart of homologous chromosomes during anaphase of meiosis

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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