Genes/Genetic diseases Flashcards
DNA is held together in what way?
Double-helix model
Complementary nitrogenous bases (A-T G-C) bind to one another
What are mutations?
What causes them?
Inherited alteration of genetic material
Caused by mutagens like radiation
Where do DNA replication and protein synthesis occur?
DNA replication occurs in nucleus
Protein synth: starts in nucleus and finishes in cytoplasm
What are the two types of human cells?
- Somatic cells: All cells other than gametes
- Gamete cells: Sperm and egg cells
What type of cells are somatic cells?
Gametes?
- Somatic cells are diploid cells (Contain 23 chromosome pairs)
- Gametes are haploid cells (contain only one member of 23 chromosomes)
What is the difference between homologous and non-homologous chromosomes?
- Homologous= Chromosome pairs with same genes at same locus (location)
- Non-homologous= Pairs with different genes at same locus
What are autosomes?
Homologous or non?
- First 22 pairs of chromosomes
- Homologous
What are the sex chromosomes?
Homologous or non?
23rd pair in humans
In females, they are homologous (XX)
In males, they are non-homologous (XY)
What process produces somatic cells?
What process produces gametes?
Somatic cells produced by mitosis
Gametes produced by meiosis
What are Karyotypes?
Ordered display of chromosomes arranged in order of decreasing size
What does euploidy refer to?
The normal number of chromosomes within a cell
(ex: 46 in humans)
What does aneuploidy refer to?
What do these cause?
Abnormal number of chromosomes in cell that usually result in genetic disorders
What are polyploid cells?
Cells that have more chromosomes than the diploid number
What are triploidy cells?
What are tetraploidy cells?
What do these conditions normally result in?
Triploidy= Zygote that has three copies of each chromosome (69 total)
Tetraploidy= Four copies of each (92 total)
- Stillbirths/miscarriages
What are aneuploidy cells?
Cells that do not contain a multiple of 23 chromosomes (45 or 47 total)
What are trisomic cells?
Cell containing three copies of one chromosome
What is monosomy?
what results?
Presence of only one copy of any chromosome
Often lethal
Down syndrome
How does it occur?
What increases the risk of it?
- Trisomy of chromosome 21
- Risk increases with mother age
Down Syndrome
- __What are common characteristics?
- mentally challenged, low nasal bridge, poor muscle tone
Turner syndrome
- What causes it?
- Characterisitics?
- Females with only one X chromosome usually inherited from mother
- Short, sterile, underdeveloped breasts
Klinefelter syndrome
- What causes it?
- Characteristics?
- Individuals with at least two X and one Y chromosome
- Male appearance, breasts, small testes
What are deletions in chromosome structure?
breakage of chromosome or loss of DNA
What are duplications in chromosome structure?
- are deletions or duplications worse?
Repeated gene or gene sequence
- Deletions are worse: better to have more than less
What are inversions of chromosome structure?
- When do they typically occur?
Reversed genetic material (ABC - CBA)
- Breakage that gets reversed during reattachment
