Year 10 Semester 2 Term 3 Flashcards
Genetics and DNA
What does the nucleus hold?
The nucleus holds all DNA and genetic information.
What is the nucleus?
The nucleus is enclosed by a nuclear membrane and controls cell activity - specifically protein production.
What does DNA stand for?
Deoxyribose Nucleic Acid
What is DNA?
A molecule that carries genetic instructions for all organisms’ development, functioning, growth, and reproduction.
What does DNA control?
DNA controls all chemical changes in cells.
What does DNA do?
DNA controls the kind of organism produced.
What is a DNA molecule?
DNA is a large molecule made of a chain of nucleotides. Each nucleotide consists of a sugar, phosphate group, and a nitrogenous base pair.
What are the most common organic bases?
Adenine, Thymine, Cytosine, and Guanine.
Describe the DNA structure
DNA is like a twisted ladder, with the phosphate and sugar in a nucleotide forming the sides of the DNA ladder, known as the sugar-phosphate backbone. Strong covalent bonds connect the sugar of one nucleotide to the phosphate of the next, and the paired strands are coiled into a double helix.
Define Gene
A section of DNA on a chromosome that contains the information for a protein or RNA, and codes for trials.
Define Chromosomes
When a cell is getting ready to divide, the DNA molecule is packed into thread-like structures called chromatin inside the nucleus..
What are chromosomes made up of?
Each chromosome is made up of DNA lightly coiled around proteins called histones.
What do Histone proteins do?
Histone proteins help DNA coil up and form its shape, found in the nucleus.
What is a Chromatid?
Two exact copies of a chromosome that are connected together.
What is a centrometre?
The point where chromatids are connected.
When are Chromatids made?
Made when new cells are going to be made.
When are Chromosomes visible?
When a cell is dividing, usually seen in the double-stranded form.
What is a Homologous Pair of Chromosomes?
Chromosomes contain the same type of genetic information. One comes from male parents, the other from the female parent.
What is a karyotype?
The general appearance of the complete set of chromosomes in the cells of a species.
What are the types of chromosomes?
Autosomes and sex chromosomes.
What are autosomes?
Body chromosomes or non-sex chromosomes ( humans have 44 or 22 pairs)
What are sex chromosomes?
The 23rd pair of chromosomes that determine the sex of the individual.
What are autosomal chromosomes?
The first 22 pairs of homologous chromosomes.
Where do we find DNA in eukaryotic cells?
In the nucleus
What kind of bonds hold the base pair together?
Hydrogen bonds
What is a somatic cell?
All cells in the body, except for germ cells
What is a germ cell?
Contain half the number of chromosomes, only found in the ovaries and testes - reproductive organs.
What is mitosis?
When a cell divides its DNA and cytoplasm, forming two new cells.
What are the phases of Mitosis?
PMAT
What is prophase?
Chromosomes condense and become visible, the nucleus disintegrates, and the mitotic spindle begins to form.
What is metaphase?
Chromosomes line up in the middle of the cell and spindle fibres attach to the centrometre.
What is Anophase?
Sister chromatids pull apart to opposite poles of the cell.
What is telophase?
Two chromatids/chromosomes move to opposite ends of the cell and 2 nuclei form.
What is Meiosis?
A special process of nuclear division that results in the production of sperm or eggs.
What is chromatin?
A combination of DNA and protein found in eukaryotic cells
What are sister chromatids?
Two identical copies of a chromatid
What is a centrometre?
A structure in a chromosome that keeps the two characteristic chromatids together.
What are spindle fibres?
Controls the movement and separation of chromosomes during cell division.
What do centrioles do?
Help in the formation of spindle fibres.
What is a nuclear envelope?
A membrane that separates the nucleus from the cytoplasm in eukaryotic cells.
What happens during interphase?
Cell growth, DNA synthesis, and Preparation for Mitosis. The cells grow, and replicate DNA and organelles.
Why is mitosis important?
Vital for the growth, development, repair, and maintenance of living organisms.
How many chromosomes do daughter cells have?
Contains 23 chromosomes known as a haploid. Avoids doubling the amount of DNA every time fertilisation occurs.
What are the main stages of Meiosis?
Meiosis 1 and Meiosis 2
What is meiosis 1?
Homologous chromosomes separate and create 2 daughter nuclei
What is meiosis 2?
2 daughter nuclei divide, sister chromosomes are separated to create 4 gametes.
What are gametes?
An organisms’ reproductive cells, also referred to as sex cells.
What happens in interphase during Meiosis
DNA replication and the cell enters the reproductive cycle with 4 copies of each chromosome.
What happens in Prophase 1 during Meiosis 1?
Chromosomes pair up in homologous pairs, and crossing over occurs. DNA condenses around histones. Nuclear membrane breaks down.
What happens in Metaphase 1 during Meiosis 1?
Homologous pairs align in the middle. Random assortment takes place.
What happens in Anophase 1 during Meiosis 1?
Homologous chromosomes attach to spindles and separate to opposite sides/poles of the cell.
What happens in Telophase 1 during Meiosis 1?
Nuclear membrane reform, chromosomes disperse followed by cytokinesis.
What is Cytokinesis during Meiosis 1?
Division of cytoplasm occurs, there may be a short pause.
What happens in Prophase 2 during Meiosis 2?
Chromosomes condense, the nuclear envelope dissolves, and centrioles migrate.
What happens in Metaphase 2 during Meiosis 2?
Chromosomes align in the middle and spindles form.
What happens in Anophase 2 during Meiosis 2?
Sister chromatids separate and spindles contract.
What happens in Telophase 2 during Meiosis 2?
Nuclear membranes reform, followed by cytokinesis, resulting in 4 non-identical daughter cells.
What does Mitosis create?
All somatic cells in the body.
What happens in Cytokinesis 2 during Meiosis 2?
Division of cytoplasm, four haploid daughter cells are produced and each cell is genetically different.
What does Meiosis create?
Gametes.
What are the similarities between mitosis and meiosis?
- Starts with a diploid cell.
- DNA replication occurs.
- Makes new cells
What is meant by crossing over of Chromosomes?
Swapping over genetic material between homologous chromosomes during meiosis.
