Meiosis and mitosis and DNA Flashcards
What is the cell cycle?
The 3 stages of change that a cell underdoes to split into two new, identical cells. It includes DNA replication, mitosis of nuclear division, then the physical splitting of one cell into two.
What is mitosis?
Mitosis is a type of cell division that produces two genetically identical daughter cells, each with the same number of chromosomes as the parent cell. It is essential for growth, repair, and asexual reproduction
What happens in stage 1 of the cell cycle?
The DNA replicates in the nucleus. To do this, the cell gets bigger making more mitochondria, ribosomes and other structures. It makes two copies of each chromosome.
What happens in stage 2 of the cell cycle?
In mitosis, one set of the two sets of chromosomes is pulled to one side of the cell’s nucleus, then the other pair goes to the other side. At the end of mitosis, the nucleus divides into two.
What happens in stage 3 of the cell cycle?
The cytoplasm of the cell splits and the ribosomes, nuclei and other organelles are divided into each cell. The cell membrane forms again around each new identical cell.
What happens to DNA during the cell cycle?
It doubles and then halves again when the cell spits in to two identical ones.
What needs to happen before a cell can divide?
The nucleus and DNA needs to replicate, there needs to also be more organelles.
Why do we need mitosis?
To double the amount of DNA, to allow cells to grow and tissues to repair.
What is a chromosome?
A structure made of DNA and proteins that carries genetic information in the form of genes.
What is a gene?
A section of DNA that codes for a specific protein, determining a particular characteristic or function.
What is DNA?
A molecule (deoxyribonucleic acid) that contains the genetic instructions for the development, functioning, and reproduction of all living organisms.
Why is it important for the chromosome number to stay the same when cells divide?
It is important for the chromosome number to stay the same during cell division (mitosis) to ensure that the new cells have the correct genetic information needed to function properly and maintain the organism’s characteristics.
What is Meiosis?
A form of sexual reproduction that creates gametes (sex cells) with half the number of chromosomes as other body cells.
Describe what the gametes are
The female gamete is the egg cell or ova, the male gamete is the sperm. Ova are made in the ovaries, sperm in the testes.
What happens to the DNA when gametes fuse in meiosis?
The little DNA in each cell combines from each parent to make the same amount of DNA as the rest of the body’s cells.
How does the DNA double then half when creating a Gamete?
The genetic information is copied so their are four sets of each chromosome instead of the usual two in a body cell. Each set makes a pair of chromatids ( that’s what they are called) the cell then divides twice so the number of cells goes from 1-> 2 -> 4 gametes each taking one of the sets of chromosomes.
How does genetic variation come from the way the DNA divides in sex cells?
Of the 4 pairs of chromosomes created in the original cell, the combination passed on is random.
What happens to the cells after fertilisation?
The number of chromosomes restores, then the new cells divide by mitosis. The number of cells increases and as the embryo develops the cells differentiate.
What is a nucleotide?
The combination of sugar, phosphate and a base ( either A, T, C or G).
What is a DNA Base?
The variable part of a DNA nucleotide which is either A, T, C and G. A always joins up to a T, C and G always pair together. A group of 3 bases code for an amino acid.
Describe the process of making proteins from a DNA’s template.
DNA is written as a template RNA and leaves the nucleus via pores in the nuclear membrane. The RNA binds to a ribosome. A carrier protein in the cytoplasm finds amino acids within the cell and joins them to the template RNA in a specific order as they are instructed by DNA. The animo acids form a chain = a protein. When complete, the protein detaches from the other structures and the process repeats. The protein chain will fold itself into a specific shape suitable for it’s function.
