Genetics and Epigenetic Flashcards
How many chromosomes does each cell contain?
(Marshall, 2017).
22 pairs of chromsosomes
1 pair of sex chromosomes.
What is the genotype?
(Marshall, 2017).
The complete genetic make up of an organism.
What is the phenotype?
(Marshall, 2017).
The observable expression of the genotype, how these genes present as physical appearance.
e.g. hair and eye colour
What do genes code for?
(Marshall, 2017).
proteins, the building blocks of cells responsible for many functions.
What are some functions of proteins?
(Marshall, 2017).
- Enzymes e.g. lipases
- Structural Support e.g. collagen
- Transport: e.g. haemoglobin.
- Hormones e.g. insulin
- Immune Response:
- Cell Signaling
- Storage and Transport of Molecules
- Defense and Protection
How are proteins made?
(Marshall, 2017).
3 nucleotides (or bases) form a code -AT,CG
These groups of three form an amino acid
Amino acids form chains by linking together and bond to form the shape of the protein
The shape of the protein determines its specific function.
How are chromosomes made?
(Marshall, 2017).
Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure
Describe dominant and recessive genes.
(Marshall, 2017).
In a chromosome pair, each chromosome is contributed to the child from the parent.
From one gene, the child may inherit a dominant gene (A) or a recessive gene (a), meaning there are many possibilties for the pair of genes inherited.
They can be both dominant (AA), both recessive (aa), or one of each.
What are the three laws of inhertience?
(Marshall, 2017).
Law of Segregation: When organisms reproduce, the traits they pass on (like eye color or height) separate out randomly. So, offspring get one version of each trait from each parent.
Law of Independent Assortment: Different traits are passed on independently of each other. Just because you inherit blue eyes from your mum doesn’t mean you’ll necessarily inherit her height or hair color.
Law of Dominance: Some traits are stronger than others. If you inherit a dominant trait (like brown eyes) and a recessive trait (like blue eyes), the dominant one will usually show up in how you look. You’d need two copies of the recessive trait to see it.
What are the different types of imperfect processes?
(Marshall, 2017).
Single point abnormalities
- Alteration in one nucleotide, missense, non-sense, insertion, deletion
Chromosomal disorders
- large scale, chromosome additions or deletions.
- no mutation in individual genes
Multifactoral inheritance aka complex cell disorders
- these involve mutliple genes
What are the different types of chromosome disorders?
(Marshall, 2017).
Monosomy- missing chromosome
Trisomy- additonal chromosome
Chromosomes can be in full, moscial or partial forms.
Mosaic has the presence of cells with different chromosomal compositions.
Partial have structural abnormalities or are missing a portion of their genetic material.
Describe missense, non-sense, insertion, deletion, framshift and duplication.
(Campbell, 2020)
A missense mutation occurs when there is a mistake in the DNA code and one of the DNA base pairs is changed, for example, A is swapped for C.
Nonsense mutation also involves a single alteration to the DNA base pair but in the case of a nonsense mutation, the change results in the production of a stop codon terminating protein synthesis prematurely.
An insertion mutation involves the addition of one (or more) nucleotide base pairs into the DNA sequence.
Deletion mutation occurs when there a piece of DNA is removed from the sequence. The size of the DNA that is removed can vary in length, from a single base pair to an entire gene or several consecutive genes.
Frameshift occurs when the aforementioned “addition” or “deletion” mutations result in a change to the gene’s reading frame, which includes groups of three bases that encode for an amino acid. The change in the reading frame alters the grouping of the bases and subsequently changes the amino acids that are encoded.
Duplication is when a piece of DNA is (abnormally) copied. This might happen once or several times, and can therefore impact the functionality of the encoded protein.
What are X-linked disorders?
(Marshall, 2017).
As females have two copies (XX), if the disorder is recessive and only present on one of the copies of the X, they become a carrier.
Males only have one copy of the X chromosome, this means a recessive gene is on the X chromosome they are affected.
The presence of a dominant mutated gene will always result in an affected individual.
Give some examples of genetic disorders.
(Marshall, 2017).
Missense- sickle cell disease
Nonsense- Cystic fibrosis
Insertion- Huntington disease, Down’s syndrome (Trisomy 21)
X-Linked Recessive- muscluar dystrophy
How are cells replicated?
(Marshall, 2017).
Interphase:
- before it divides the cell has a period of growth and prepration
- this phase has 3 stages: G1, S, and G2
- in the S stage (synthesis) DNA replication occurs, reuslting in the cells genetic material being duplicated
Mitosis:
- when the duplicated chromosomes are distributed into two daughter cells
- has several stages: prophase, metaphase, anaphase, and telophase.
- Prophase: chromatin condenses into visible chromosomesand nucleus breaks down. Spindle fibers begin to form and attach to the centromeres (middle) of the chromosomes.
- Metaphase: chromosomes align along the middle of the two poles, along the equator of the cell
- Anaphase: the chromosomes separate and move toward opposite poles of the cell, pulled by the spindle fibers.
- Telophase: the separated chromatids reach the poles, and new nucleui form around them. The chromosomes begin to decondense back into chromatin.
Cytokinesis: the division of the cytoplasm, resulting in the formation of two distinct daughter cells.
Result it two identical daughter cells, each containing a complete set of chromosomes and organelles.
This process ensures the growth and renewal of tissues and the transmission of genetic material to offspring in organisms.
