Genetics Flashcards
Describe the significance of crossover in genetic inheritance.
Crossing Over
This process results in new combinations of alleles in the gametes (egg or sperm) formed, which ensures genomic variation in any offspring produced.
23.4 Explain co-dominance in relation to the ABO blood group.
What are chromosomes?
Chromosomes carry DNA in cells.
What is the function of DNA?
** Improve answer**
DNA is responsible for building and maintaining your human structure.
What is a gene?
Genes are segments of your DNA which give you physical characteristics that make you unique.
What is a condon?
A sequence of 3 bases in a gene
Define genome
All the coding and non-coding genetic material of an organism
Define proteome
The entire range of proteins that a cell is able to produce
Define introns
Segments of DNA which do not code for amino acids/ proteins
Does prokaryotic DNA contain introns?
No
Define exons
Base triplet coding for amino acids
What is it called when a gene exists in more than one form?
Alleles
A pair of matching chromosomes are called…
homozygous chromosomes
What is a degenerate code?
More than one base triplet codes for the same amino acid
Are the hydrogen bonds between the folded tRNA molecule between complementary bases?
Yes
When folded, the hydrogen bonds will only be found between A & T and C & G
Define the non-coding base sequence and describe where the non-coding multiple repeats are positioned in the genome.
DNA that does not code for order of amino acids
Found between genes
How does a gene code for a polypeptide?
Base triplets code for amino acid SEQUENCE
Similarities between eukaryotic and prokaryotic DNA
Nucleotides joined by phosphodiester bonds
The nucleotide structure is identical
The two strands in a DNA molecule are held together by …
Hydrogen bonds
The term haploid refers to cells that have
23 chromosomes
The presence of an extra chromosome in a diploid cell is called…
trisomy
Meiosis is a type of cell division that occurs in the…
reproductive organs
If an allele must be present on both the maternal and paternal chromosomes to be expressed within the phenotype of the offspring, it is said to be…
recessive
The location of a gene on a chromosome is where?
On its locus
The genotype is determined by what?
DNA sequencing
Define Mitosis
The part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with identical copies of DNA produced by the parent cell during DNA replication.
Define Meosis
Meiosis is a form of nuclear division that produces haploid cells from diploid cells. It produces gametes that are used in sexual reproduction.
What two things does a gene code for
The amino acid sequence of a polypeptide
Functional RNA
What determines the order of amino acids
The order of the bases
What is a degenerate code?
More than one base triplet codes for the same amino acid
What is functional RNA?
RNA molecules other than mRNA that have a role in protein synthesis E,g, tRNA and rRNA
How many pairs of chromosomes do humans have?
23
What does it mean by the genetic code is universal?
The same base triplet codes for the same amino acid in all organisms
What is a chromosome comprised of (structure)?
DNA molecule wrapped around a histone
What parts of DNA are non-coding x2?
Multiple repeats
Introns
Describe how DNA and RNA differ based on each of their FUNCTIONS during protein synthesis.
- DNA stores the information for protein synthesis.
- RNA carries out the instructions encoded in DNA.
What is the 1st step of protein synthesis?
Unzipping:
DNA double helix unwinds to expose a sequence of nitrogenous bases.
- Hydrogen bonds are broken.
What is the 2nd step of protein synthesis?
Transcription:
A copy of one of the DNA strands is made. This copy is made of mRNA, which travels from the nucleus into the cytoplasm of the cell, where protein synthesis occurs.
What is the 3rd step of protein synthesis?
Translation (Initiation):
mRNA couples w/ ribosome & tRNA brings free amino acids to ribosomes.
What is the 4th step of protein synthesis?
Elongation:
- Anticodon of tRNA recognizes codon on mRNA.
- Ribosome adds amino acid to growing chain of amino acids
What is the 5th step of protein synthesis?
Termination:
As polypeptide grows, it folds to form a protein and continues to grow until a stop codon is encountered. Then, the ribosome releases polypeptide.
Define Co-dominance
Co-dominance – Some genes may not show complete dominance but rather share the effect (phenotype) between the two alleles e.g. AB blood groups.
Define Genetic imprinting
Genetic imprinting – involves a sex-specific process of chemical modification to the gene (or genes) so that the alleles are unequally expressed depending on the sex of the parent carrying the modified gene.
Define Polygenic
Polygenic - most often several genes are responsible for any given trait e.g. skin colour. Diseases such as heart disease, diabetes and some cancers are often polygenic.
Define Multi-factorial
Multifactorial: Involve a complex interaction of the genes with the environment (e.g., cigarette smoke, sunlight, etc.).
What happens in Mitosis?
- somatic or body cells
- 1 division
- 2 genetically identical daughter cells
- identical/same amount of chromosomes in daughter cells
- the purpose is for growth
What happens in Meiosis?
- germ or sex cells
- 2 divisions
- 4 daughter cells
- half the number of chromosomes in daughter cells
- the purpose is for reproduction
What is the main function and product of mitosis?
The main function of mitosis is growth. You end up with two new daughter cells because you start with one cell. That cell grows, prepares for division, and divides into two new cells. The cycle continues in each of the two new cells.
What is the main function and product of meiosis?
The main function of meiosis is reproduction. You end up with four sex cells because the cell that you start with separates, forming two new cells. Then, the two new cells that are formed each separate into two more cells.
Define Allele
One of two or more versions of a genetic sequence at a particular region on a chromosome.
Define Locus
The position of a gene on a chromosome
Define Genotype
the genetic constitution of an organism.
Define phenotype
The observable physical properties of an organism
Define homozygosity
You inherit two identical alleles.
Define heterozygosity
Having inherited different versions (alleles) of a genomic marker.
Define mutation
A change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide
Define chromosomes
Structures in a cell that contain genetic material, also known as DNA.
Define autosomes
An autosome is 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).
Autosomal Recessive Inheritance: Are affected individuals homozygous or heterozygous? Why?
Homozygous
You need 2 affected recessive alleles to show the disorder.
Autosomal Recessive Inheritance: Carriers are homozygous or heterozygous?
Heterozygous
Because If the disorder are on recessive alleles, then they need to homozygous to be expressed, hence they are carriers if they are only carrying one.
Autosomal Recessive Inheritance: With carrier parents, what is the likelihood of the child being:
Normal
Carrier
Affected
Normal = 25%
Carrier = 50%
Affected = 25%
Autosomal Recessive Inheritance: With 1 carrier parent and 1 normal parent what is the likelihood of the child being:
Normal
Carrier
Affected
Normal = 50%
Carrier = 50%
Affected = 0%
Autosomal Recessive Inheritance: With 1 affected parent and 1 normal parent, what is the likelihood of the child being?
Normal
Carrier
Affected
Normal = 0%
Carrier = 100%
Affected = 0%
Define sex-linked traits.
Traits that are inherited with sex chromosomes
Define Autosomal Linked Trait.
A trait inherited from the 22 pairs of autosomes (non-sex chromosomes).
Define y linked traits.
Only males are affected, it is passed from father to all sons and does not skip generations.
Define x linked traits.
recessive or dominant genes carried on X only code traits.
What do X-linked recessive alleles do?
Affects more males, and they usually have unaffected mothers (trait skips generations). Never passed father to son. A carrier mother will pass trait to 1/2 her sons. Affected fathers will have carrier daughters.
What do X-linked dominant alleles do?
- Transmitted through both parents.
- often, more females are affected
- Mothers transmit to 50% of daughters and sons; fathers transmit to all daughters but no sons.
- Both genders are affected. Doesn’t skip generations.
- Affected sons must have an affected mother but affected daughters can have either parent affected.
