Chromsome Structure Flashcards
Where is DNA found in animal cells, plant cells and prokaryotic cells?
Animal - Nucleus and mitochondria
Plant- nucleus, mitochondria and chloroplasts
Prokaryote - cytoplasm and plasmids
What is chromatin?
DNA in chromosomes that is complexed with protein
What are the 2 types of interphase chromatin?
- Euchromatin - DNA that is active (being expressed as protein
- Heterochromatin - Mostly inactive DNA - CONSTITUTIVE AND FACULATIVE
What are the 2 types of Heterochromatin?
-Constitutive - never expressed, near centromere mostly repetitive DNA
-Faculative - sometimes expressed
Which is the short and long arm of the chromosome?
P is the short arm and Q is the long arm
What phase are chromosomes in when being looked at?
Metaphase
What are sister chromatids?
The identical double structures the chromosome has been replicated into during dividing
What are the proteins called that keeps the DNA compact?
Histones
What does Metacentric mean?
The centromere is close to the midpointä
What does Submetacentric mean?
The centromere is removed from the midpoint so a short arm (p arm) and long arm (q arm) can be seen
What does Acrocentric mean?
The centromere is near the end and the short arm only can be seen - sometimes has satellites on end of arm
What does Telocentric mean?
The centromere is at one end and only one arm can be seen
What is the complete set of diploid chromosomes called?
Karyotype
What treatments can be used to aid oin distinguishing between chromosomes?
Giemsha staining - reveals G bonding patterns
What is Aneuploidy?
When an individual is missing either a chromosome from a pair (monosomy) or has more than 2 chromosomes of a pair (trisomy)
Why might Aneuploidy occur?
Due to abnormalities in meiosis
What are examples of Aneuploidy?
Down Syndrome Trisomy 21, Trisomy 18 Edwards Syndrome
What is Polyploidy?
Occurs in cells when there are more than 2 sets of chromosomes
How does Polyploidy occur?
Due to abnormal cell division during mataphase in meiosis
What are deletions?
A portion of the chromosome is missing or deleted. Terminal or interstitial
What are the effects of Deletions?
-Insufficient gene products
-Unmansking of mutant alleles on normal chromosomes
–Example; Cri de chat
What are Duplications?
A portion of the chromosome is duplicated resulting in extra genetic material
What are Inversions?
A portion of the chromosome has broken off, turned upside down and reattached, therefore the genetic material is inverted
-Pericentric - both arms
-Paracentric - one arm
What are Rings
A portion of a chromosome has broken off and formed a circle or ring - can happen with or without loss in genetic material - epilepsy and mental retardation
