Lesson 1 - Intro to Genetics Flashcards
(11 cards)
What are DNA and Nucleotides?
DNA is a double helix (2 strands)
Nucleotides are the basic unit of nucleic
acid
DNA molecule is made up of sugar,
phosphate (backbone) and
nitrogenous base (middle)
4 types of nitrogenous bases paired
this way:
A – adenine and T – thymine
C – cytosine and G – guanine
When and Why Chromosome Duplication Happen
When do chromosomes duplicate?
- During interphase before mitosis
Why do chromosomes need to duplicate? What is the Purpose?
- Chromosome number of the same organism can be kept the same
The Cell Cycle
In order to grow and replicate, Eukaryotic cells go through an orderly sequence known as The Cell Cycle
The Cell Cycle consists of two main stages:
- A growing stage, known as the Interphase
- A cell division stage, known as Mitosis and Cytokinesis
Interphase (G1, S, G2 Phases)
Interphase is the growing stage of the cell cycle
The cell spends 90% of its time during the
interphase
The cell gets ready for mitosis
During G1 Phase: Nucleolus
can be seen
During S-Phase: Chromatin in the nucleus begins to condense and becomes visible as chromosomes
The nucleolus disappears
Chromosomes pair up, then duplicate 🡪 23 pairs of duplicated chromosomes
What are the two processes of M-Phase?
The M-Phase includes two processes:
- Mitosis
Division of Nucleus
- Cytokinesis
Division of Cytoplasm
Names of the 4 Stages of Mitosis
Mitosis is made of 4 stages:
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase
Two pairs of centrioles move to opposite ends of the cell
Spindle fibers extend from centrioles to the centromeres
In prophase, the nuclear membrane dissolves (This part of prophase is sometimes called Prometaphase. It is between prophase and metaphase)
Metaphase
Spindle fibres align the chromosomes along the middle of the cell
This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome
Anaphase
The sister chromatids separate and move to opposite sides of the cell
Telophase
Chromatids arrive at opposite poles of the cell
New membranes form around the daughter nuclei
The chromosomes disperse and are no longer visible
The spindle fibres disappear
Before the Telophase ends, Cytokinesis occurs
Cytokinesis (Cytoplasmic Division)
The separation of the cytoplasm and its content into equal parts
This process begins before mitosis is complete
About half of the cytoplasm, containing about half of the organelles, goes to each daughter cell
Cytoplasmic division is different in animal cells and plant cells.
In animal cells, the cell membrane pinches together in the middle, separating the cytoplasm into equal parts and creating two new cells
In plant cells, a new cell wall forms along the middle, creating two new cells
