Bio genetics

What is Chromatin

A mixture of DNA and proteins that make up the chromosomes

What are sister chromatids

A sister chromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere.

Homologous chromosomes

Homologous chromosomes are made up of chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci. One homologous chromosome is inherited from the organism's mother; the other is inherited from the organism's father.

Tetrad

A tetrad is composed of two homologous chromosomes, each containing two sister chromatids. Therefore, it is composed of four chromatids that line up during meiosis.

Gene

A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.

Allele

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Locus

a term that we use to tell us where on a chromosome a specific gene is.

Codominance

a form of inheritance wherein the alleles of a gene pair in a heterozygote are fully expressed. As a result, the phenotype of the offspring is a combination of the phenotype of the parents. Thus, the trait is neither dominant nor recessive.

Polygenic dominance

an interaction between alleles from a polygenic trait (a trait that involves multiple genes) where one allele dominates the other alleles. Eye color is an example of polygenic dominance where the brown (BB, Bb) allele dominates the alleles for blue (bb) and green (GG, Gg).

Incomplete dominance

a form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype.

How can chromosomal mutation lead to a genetic disorder

Genetic disorders can be: Chromosomal: This type affects the structures that hold your genes/DNA within each cell (chromosomes). With these conditions, people are missing or have duplicated chromosome material. Complex (multifactorial): These disorders stem from a combination of gene mutations and other factors.

What are the stages of mitosis

Interphase, prophase, metaphase, anaphase, telophase, cytokinesis

What are the stages of meiosis

interphase, prophase I, metaphase I, anaphase I, telophase I, cytokinesis, interphase II, metaphase II, anaphase II, and telophase II.

Asexual reproduction

a mode of reproduction in which a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to each other, i.e., they are the clones of their parents. Asexual reproduction is observed in both multicellular and unicellular organisms.

Sexual reproduction

a type of reproduction that involves a complex life cycle in which a gamete with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes

Genotype

The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location.
ex: BB, Bb, bb

Haploid

Haploid refers to the presence of a single set of chromosomes in an organism's cells (n). In humans only the sperm and egg are haploid. Formed in meiosis

Diploid

Diploid, as the name indicates, contains two sets of chromosomes (2n). Undergos mitosis

What are autosomes

one of the numbered chromosomes, as opposed to the sex chromosomes. Humans have 22 pairs of autosomes and one pair of sex chromosomes (XX or XY). Autosomes are numbered roughly in relation to their sizes.

Homozygous

having two identical alleles of a particular gene or genes.
"homozygous embryos"
ex: BB or aa

Heterozygous

refers to having inherited different versions (alleles) of a genomic marker from each biological parent. Thus, an individual who is heterozygous for a genomic marker has two different versions of that marker.

Define heredity

the passing on of physical or mental characteristics genetically from one generation to another.
ex: eye colour, hair colour, height

Phenotype

refers to an individual's observable traits, such as height, eye color and blood type. A person's phenotype is determined by both their genomic makeup (genotype) and environmental factors.

Trisomy

A medical term for having an extra copy of a chromosome is 'trisomy.' Down syndrome is also referred to as Trisomy 21. This extra copy changes how the baby's body and brain develop, which can cause both mental and physical challenges for the baby.

Monosomy

the absence of one member of a pair of chromosomes. Therefore, there are 45 chromosomes in each cell of the body instead of the usual 46

Nondisjunction

causes abnormal number chromosomes in all the cells called aneuploidy or in some cells called mosaicism. Some of the important examples are: Down's syndrome – Trisomy of autosomes, i.e. chromosome 21

random assortment

The random organisation of chromosomes in the middle of the cell during the first stage of meiosis, which further increases genetic diversity

Independent assortment

the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene

What is a Karyotype

is an individual's complete set of chromosomes. The term also refers to a laboratory-produced image of a person's chromosomes isolated from an individual cell and arranged in numerical order. A karyotype may be used to look for abnormalities in chromosome number or structure

What is an enucleated egg

When the ovum's nucleus is removed, the cell loses its genetic information. This has been blamed for why enucleated eggs are hampered in their reprogramming ability. It is theorized the critical embryonic genes are physically linked to oocyte chromosomes, enucleation negatively affects these factors

Polar body

a small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have the ability to be fertilized. It is named from its polar position in the egg

Double helix

a term used to describe the physical structure of DNA. A DNA molecule is made up of two linked strands that wind around each other to resemble a twisted ladder in a helix-like shape

Point mutation

a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences that are moderately predictable based upon the specifics of the mutation.

one nitrogenous base is substituted, added or deleted

Restriction enzymes

is a protein isolated from bacteria that cleaves DNA sequences at sequence-specific sites, producing DNA fragments with a known sequence at each end. The use of restriction enzymes is critical to certain laboratory methods, including recombinant DNA technology and genetic engineering

Genome

all of the genetic material in an organism. It is made of DNA (or RNA in some viruses) and includes genes and other elements that control the activity of those genes

Recombinant DNA

involves using enzymes and various laboratory techniques to manipulate and isolate DNA segments of interest. This method can be used to combine (or splice) DNA from different species or to create genes with new functions

Pedigree

A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors from one generation to the next, most commonly humans, show dogs, and race horses

What are sex chromosomes

A type of chromosome involved in sex determination
ex: XX (female) and XY (Male)

Difference in mitosis between plants and animals

Animal cell constricts at the equatorial region to divide in two daughter cells. Plant cell divides by depositing a partition plate at the equator of the cell. Plant cell develops anastral spindle while animal cell develops astral rays at the poles during division.

Location of meiosis

Meiosis is a special version of cell division that occurs only in the testes and ovaries; the organs that produce the male and female reproductive cells; the sperm and eggs

Genetic variation of meiosis

meiosis creates new combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes. Such exchange means that the gametes produced through meiosis exhibit an amazing range of genetic variation

Gametogenesis

the process in which cells undergo meiosis to form gametes.

Monohybrid crosses

is a cross between two organisms with different variations at one genetic locus of interest. The character being studied in a monohybrid cross are governed by two or multiple variations for a single location of a gene

Dihybrid crosses

a mating experiment between two organisms that are identically hybrid for two traits

Hybrid

an offspring of two animals or plants of different subspecies, breeds, varieties, species, or genera.

Sex-linked crosses

mating a male with two recessive k genes (i.e., kk) with a female that has the dominant form of the gene (indicated as K_). Offspring from this cross will be fast-feathering females like their father and slow-feathering males like their mother, as shown below

Manipulating genomes

Genome editing is a method for making specific changes to the DNA of a cell or organism. It can be used to add, remove or alter DNA in the genome. Human genome editing technologies can be used on somatic cells (non-heritable), germline cells (not for reproduction) and germline cells (for reproduction)

What are the parts of a DNA molecule

deoxyribose sugar (5-carbon ring), Phosphate group (negative charge), niteogenous base. They assemble together to form a necleotide

Types of nitrogenous bases

Adenine (A) Guanine (G) Thymine (T) Cytosine (C)
Apple Tree, car in garage
A+G=T+C

What bind together to make a backbone of one strand on a double helix

Deoxyribose sugar and phosphate

Complementary strands

two single strands of dna in which the nucleotide Sequence is such that they will bind as a result of base pairing throughout their full length