L9 Mitosis and Meiosis Flashcards
Chromosome act as the vehicles that must…
Pass on genetic information accurately
Mitosis produces…
2 genetically identical daughter cells
Mitosis is the basis for asexual reproduction in…
Single-celled eukaryotes
In humans mitosis plays an important part in (4)…
- Embryonic development
- Skin cells
- Wound healing
- Reticulocytes (immature red blood cells)
Uncontrolled mitosis can lead to…
Tumor formation
In mitosis a cell goes from Xn to Yn which divides to form two Xn cells.
X = 2 Y = 4
The 5 phases of mitosis are:
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
The kinetochore is…
The protein at the centromere, which serves as an attachment point for the mitotic spindles
Spindle fibres are…
Microtubules running between the two poles of the cell, creating the axis for separation of the chromosomes
The centriole generates spindle fibres and has a (structure)…
9 triplet microtubule structure
Interphase is divided into 4 possible phases…
- G0
- G1
- S
- G2
Meiosis is the cell division which produces…
Gametes (sperm, egg cells, spores, pollen)
Unlike mitosis, meiosis results in (2)…
Haploid gametes (1n) and genetic variability
During meiosis I, genetic reassortment occurs through (2)…
‘Crossing-over’ and independent assortment
The chiasma is the…
Physical connection between non-sister chromatids during meiosis I
During interphase between meiosis I & II DNA replication ( occurs / does not occur / sometimes occurs )
Does not occur ❌
Meiosis prophase I can be subdivided into 5 phases, these are…
- Leptonema (Leptotene)
- Zygonema (Zygotene)
- Pachynema (Pachytene)
- Diplonema (Diplotene)
- Diakinesis
Meiosis I, prophase I - 1. Leptotene
Duplicated chromosome starts to condense
Meiosis I, prophase I - 2. Zygotene
Synapsis begins. Synaptonemal complex forms, forming a ‘bivalent’ (a.k.a ‘tetrad’)
Meiosis I, prophase I - 3. Pachytene
Synapsis completed. Crossing over occurs
Meiosis I, prophase I - 4. Diplotene
Chiasma becomes visible. Synaptonemal complex begins to disappear
Meiosis I, prophase I - 5. Diakinesis
The nuclear envelope fragments
Meiosis II is similar to…
Mitosis
The production of male gametes is continuous. In contrast, oogenesis pauses at prophase I in the embryo, resuming…
Prior to ovulation (years later)
Aneuploidy
Chromosome number is not an exact multiple of the haploid number
Non-disjunction results in aneuploid gametes. Non-disjunction is…
The failure of chromosome pairs to separate
Trisomy is a polysomy with…
Three chromosomes 3️⃣
Trisomy 21 results in…
Down Syndrome
The centrosome is comprised of…
A pair of centrioles
When does crossing over occur?
Prophase I
Why is crossing over important?
To increase genetic diversity
