Mitosis and Meiosis Part 1 Flashcards
What is Meiosis or Mitosis
Is the processes in which cell division occurs, meaning cells are copied to give daughter cells or progeny
What does Diploid mean
Carry two copied of each chromosome
- maternal and paternal
What does mitosis create
Identical Daughter cells
What does Meiosis create
Haploid cells are formed - Important to create ovocytes or sperm cells
- Only has one copy thus either Maternal OR paternal
What is Down syndrome
Down syndrome is the trisomy (Three copies) of chromosome 21
What causes down syndrome
Down syndrome is caused by Non-disjunction
(the failure of homologous chromosomes or sister chromatids to separate)
during meiosis
What does Down syndrome Cause
Delayed growth
Characteristic facial features
Mild intellectual disability
What is the cell cycle
A combination of cell growth, replication and division that produces new cells
Can cell cycle differ
what part of the cycle varies in length
The length of the cell cycle can differ between animals all and different cell types
Some cancer cells - interphase can only an hour
Other cells - interphase can last one year
M phase tends to remain constant
What is the difference between chromosomes and chromatids
Chromosomes that have been replicated contain 2 sister chromatids
When can the Classical X shape of a chromosome be seen
Can only be seen during the metaphase, phase of the cell cycle.
What does the classical X shape of a chromosome show
The classical X-shape is replicated chromosome containing two identical DNA molecules
How do you give a gene a location
(Xq 26.2)
Found on the X chromosome
On the (long) Q arm
26.2 cM (centrimorgans away from the centromere)
Where are telomeres found
At the end of the chromosomes
What does the telomere contain does it vary
Telomere are repeat sequences (TTAGGG) at each of a chromosome / chromatid
Doesn’t very ( even between different species )
What does the Telomere do
Protects the ends of the chromosomes during replication, thus the entire number of genes if copied and no information is lost during replication.
What do Centromeres do
Centromeres link the sister chromatids and consists of repetitive sequences
What are the 4 different ways chromatids are linked to chromosomes
Metacentric - Centromere found in centre
Submetacentric - Centromere is near to the top
Acrocentric - Centromere is closer to the top
Telocentric - Centromere is at the very end of the chromosome
How can chromosome be grouped
How many groups are there
Chromosomes can be grouped according to size and shape
Seven groups based upon size, position of
centromere and local differences
How do you Stain Chromosomes
G-banding can be used to stain chromosomes
Enzymatic digestion followed by a Giemsa stain
This creates a characteristic banding pattern used to identify chromosomes
Can identify translocations, duplications
loss of Y chromosomes….
How can painting be used to identify chromosomes
Fluorescent markers label the
different parts of chromosomes
Why is identifying positions of chromosomes important
give an example
Can be used to diagnose some diseases
Turner syndrome – one X chromosome missing
Where are the nucleuses during interphase
During interphase chromosomes are compacted in the nucleus
Are non-sister and sister chromatids identical
Sister chromatids contain identical copies of genes
Non-sister chromatids are not identical (may differ by the alleles) – derived from the maternal and paternal genomes
