Mitosis, Meiosis, Mistakes & DNA structure (QUIZ) Flashcards
What is GENETICS?
The branch of biology dealing with heredity and the variations of INHERITED CHARACTERISTICS
What is HEREDITY?
The PASSING OF TRAITS from parents to offspring
What are TRAITS?
CHARACTERISTICS or FEATURES of an organism
–> Nose, Shape, height
Heredity: Explain DOMINATE gene (provide example)
Variant of a gene on a chromosome masking or OVERRIDING the effect of a DIFFERENT VARIANT of the same gene. (Aa –> A is dominant)
AA –> brown
Aa –> brown
aa –> orange
OBSERVABLE HUMAN CHARACTERISITICS: Rolling tongue, cleft chin, bent pinky.
Heredity: Explain RECESSIVE gene (provide example)
Variation of a gene on a chromosome that will only be expressed if TWO RECESSIVE genes are present (no dominant trait is present). (aa –> no dominant gene)
AA –> brown
Aa –> brown
aa –> orange
OBSERVABLE HUMAN CHARACTERISITICS: Non-rolling tongue, no cleft chin, straight pinky.
Cell Division (6)
- The continuity of life is based on the reproduction of cells, or cell division.
- Single-celled organism
- -> Binary fission aka asexual reproduction. - Multi-celled organism
- -> Cells in bone marrow make new red blood cells. - Most cell division involves the distribution of IDENTICAL GENETIC MATERIAL to two daughter cells.
- The molecule DEOXYRIBONUCLEIC ACID (DNA) contains our genetic information.
- A cell’s DNA must be copied before the cell can divide - this ensures the daughter cell each ends up with a complete genome.
What is a GENOME?
The COMPLETE set of GENETIC MATERIAL of an organism or virus.
It provides all of the INFORMATION the organism requires to FUNCTION. In living organisms, the genome is stored in long molecules of DNA called chromosomes.
What is a GENE?
A segment of DNA molecule that codes for a particular trait.
–> A gene is a portion of a DNA molecule that carries information (code) that helps to produce a particular trait of an organism (hair, skin, eyes, etc.)
What is a LOCUS?
The location of a gene on a chromosome.
–> Each gene occupies a specific location, or locus, on a chromosome.
For all cells, it is the same placement, however the coding varies
from person to person.
What is the difference between CHROMATIN and CHROMOSOME?
Include Sister chromatids and centromere
CHROMATIN:
A mass of thread-like strands of DNA. When a cell is NOT dividing, DNA is in the form of long, thin chromatin fibres in a RELAXED STATE.
CHROMOSOME:
Cellular structures containing a very long DNA molecule and associated PROTEINS that are COMPRESSED and packed.
–> Found in the NUCLEUS
SISTER CHROMATIDS:
Each duplicated chromosome has two sister chromatids. Sister chromatids are JOINED COPIES of the original chromosome.
CENTROMERE:
Region on a chromatid containing specific DNA sequences where the chromatid is ATTACHED most closely to its SISTER.
–> Created by protein bound to the centromeric DNA sequence and gives the chromosome a NARROW “waist”
–> The part of the chromatid on either side of the centromere is referred to as an ARM.
What are the 3 STAGES of the CELL CYCLE (5, 1, 3)
- INTERPHASE:
- The stage which cells are BETWEEN division, is called interphase.
- During interphase, the cell grows and carries out its NORMAL FUNCTIONS.
- The chromosomes in the nucleus form a mass of THRED LIKE STRUCTURE called CHROMATIN
- The REPLICATION (s phase) of chromosomes as well as cellular components during interphase result in pairs of SISTER CHROMATIDS, each containing exactly the SAME GENES at the same LOCI.
- Each original chromosome and its duplicate remain attached by a structure called the CENTROMERE. While attached they are referred to as sister chromatids.
- MITOSIS:
- Genetic material in the nucleus is DIVIDED EQUALLY into two new nuclei.
- CYTOKINESIS:
- Mitosis is followed immediately by cytokinesis, the stage of the cell cycle when the CYTOPLASM OF A CELL IS DIVIDED to form two new cells.
- Although the nucleus is divided during mitosis, the division of the CELL CONTENT in two new daughter cells happens during cytokinesis.
- -> There are two nuclei in a cell at once. - CLEAVAGE FURROW develops to “cut” the two cells apart.
- -> Cell plate in plants
- -> During the growth stage of the cell cycle, additional copies of organelles are formed.
More about INTERPHASE + purpose (4)
- G1 - beginning of cell growth.
- S - DNA is synthesized and duplicates.
- G2 - Cell undergoes its FUNCTIONS (growing + producing proteins)
–> Purpose: Replenish dead or dying cells, to allow an organism to grow and develop.
What are the CHECKPOINTS intended for? (2)
- Regulatory points at which the cell examines internal and external cues and decides whether or not to move forward with division (security check if there are ant issues with the cell)
- The spindle checkpoint: at the transition from metaphase to anaphase.
G1 CHECKPOINT (What is it looking for) (7)
- SIZE: is the cell large enough to divide?
- NUTRITION: Are all the needed nutrients present in the environment?
- MOLECULAR SIGNALS: Is the cell receiving positive cues (such as growth factors) from its neighbours.
- MECHANICAL SIGNALS: Is the cell attached to a support? Is it crowded by neighbours.
- DNA INTEGRITY: Is any of the DNA damaged?
- If the cell does not pass G1 checkpoint, it may enter G0 resting phase –> in order to be fixed or to die.
- Once cell passes G1, it is committed to divide.
G0 phase (3)
- Resting phase
- -> Nerve cells in the brain stop dividing when the brain is developed and cannot reenter the cell cycle (CANNOT GO BACK INTO G1) - Liver cells can be in G0 but re-enter the cell cycle if the liver is damaged or needs repair (stays in G0 until ready to be sent back)
