Ch. 6 - Chromosomes and Cell Divison Flashcards
Why are offspring genetically different from their parents?
- The alleles come from 2 parents.
- Crossing over.
- Reassortment of homologues.
Define nondisjunction.
The unequal distribution of chromosomes during meiosis due to the centromeres.
What are the products of mitosis & meiosis?
Mitosis: 2 diploids (identical)
Meiosis: 4 haploids (unique)
What is the difference between Anaphase 1 & 2?
In anaphase 2, the sister chromatids are pulled apart and separated by spindle fibers instead of the 2 being pulled apart together.
Explain the steps in Prophase 1?
- Replicated chromosome condense.
- Spindle is formed
- Homologous pairs of sister chromatids come together and cross over.
- Nuclear membrane disintegrates.
Define crossing over.
When the maternal and parental chromosomes change parts.
What separates during meiosis 1 & 2?
Meiosis 1 separates homologous chromosomes. Meiosis 2 separates sister chromatids.
During meiosis, how many daughter cells are created? How about mitosis!
4; 2
What is a sister chromatid?
One of the two identical copies of a chromosome created during replication, held together by a centromere.
What are homologous?
Maternal and paternal copies of chromosome.
What are two important features about meiosis?
1) reduces the amount of genetic material in gametes.
2) all gametes are different.
Define gametes.
Sex cell.
What is meiosis?
The generation of sperm and egg. A process that enables organisms to make special reproductive cells.
Define a diploid.
Has 2 copies of each chromosome.
Define a haploid.
A cell that has 1 copy of each chromosome.
What is a somatic cell?
An asexual cell (every cell in our body).
Why does cancer live forever? Why do they spread so much?
The telomeres rebuild. They don’t stick together which causes them to run throughout the body.
What is a tumor?
Unregulated cell division. They ignore the signals that the area is full so they keep producing and pilling up on top of each other.
What is the cause of cancer?
A cell that was supposed to die but didn’t, and kept growing, dividing, leading to unrestrained cell growth.
What happens during Anaphase?
The chromatids split and each part is pulled away by a spindle fiber.
What happens during Metaphase?
The chromosomes all meet in a center line called the equator.
What happens during Telophase?
Two cells begin to form from the one cell.
What is Cytokinesis?
The end result of mitosis (2 daughter cells).
What are the steps of mitosis?
1) prophase
2) metaphase
3) anaphase
4) telophase
What is apoptosis?
Pre-planned process of cell suicide. (End of a cells life)
What are the 3 reasons for mitosis?
1) growth
2) repair
3) replacement
What is the purpose of mitosis?
To enable existing cells to generate new, genetically identical cells.
How do genetic mutations occur.
An error can occur during replication.
What happens during replication?
It unwinds, pairs (rebuild) and gets shipped off.
What happens in all the Interphase phases?
Gap 1: primary growth
Syntheses: preparations for division
Gap 2: 2nd growth period
How do prokaryotes divide or reproduce?
Binary fusion, or asexually (duplicate then divide)
What are telomeres?
A protective cap at the end of DNA.
How does a telomere disappear? What happens when all the telomeres are gone?
Every time a cell divides, the telomere looses a little bit. Once the telomere is gone, the DNA starts getting eaten away causing cancer, diseases, ect.
