Unit 3 Flashcards
What are nucleotide made of?
A sugar- phosphate backbone and a nitrogenous base (A, T, G, C)
What are the nitrogenous base pairings?
Adenine matches with Thymine
Guanine matches with Cytosine
Who created the structural model of DNA?
James Watson and Francis Crick in 1952
What are histones?
Histones are the proteins wounded around DNA.
What is the importance of the base pairing in DNA?
The base pairing in DNA makes up the genetic code of an organism (genome is our whole genetic code).
What are Karyotypes?
A persons particular arrangement of chromosomes. Chromosomes can range in side (humans have 23 pairs and 46 in total)
What are autosomal chromosomes?
Regular chromosomes are autosomal (humans have 22 pairs of autosomal)
What are sex chromosomes?
Sex chromosomes tell the sex of the organism and is placed last in the chromosome picture line-up (XX for female, XY for male)
How do cells use DNA?
All DNA in the body has the same DNA but uses only a part of the DNA to do their job.
What is Asexual reproduction?
Asexual reproduction is done from a single-celled parent by cell division (mitosis). Offspring is genetically identical to parent
Advantages of asexual reproduction?
- Parents organisms do not need to seek out a mate to reproduce
- Specialized mating behaviours are not needed
- No specialized anatomy
What is Budding?
When an offspring develops from outside of the parent organism. When their offspring grows large enough, it detaches and lives on its own. Ex. Hydra
What is Fragmentation?
A piece of the parent organism breaks off and matures into its own. Ex. mushrooms grow spores that develop into mushrooms
What is the cell cycle?
The cells cycle of life. Starts in the growth stage (Interphase) then the division stage which is much shorter and split into to parts: Mitosis (prophase, metaphase, anaphase, and telophase) and cytokinesis.
What happens in Prophase?
- Chromatin (DNA) condenses into
chromosomes - Centrioles move to opposite ends of the cell
- Spindle fibers form from the centrioles
- Nuclear membrane dissolves
What happens in Metaphase?
- Spindle fibers attach to centromeres
- Chromosomes align along the equatorial plate
What happens in Anaphase?
- Spindle fibers shorten
- Centromere splits and pulls chromatids to opposite ends of the cell
What happens in Telophase?
- Chromosomes relax into chromatin
- Nuclear membrane reappears
- Two new nuclei are formed
- Spindle fibers disappear
What happens in Cytokinesis?
- the cytoplasm divides
- In animal cells, cleavage furrows are formed
- In plant cells, cell plates are formed
Disadvantages of sexual reproduction?
- Specialized organs are needed to produce the sex cells
- Need courtship techniques to mate like bright colours but that could also attract predators
- May require the lost of a resource such as nectar in flowers
- The offspring may be weak or unable to survive when combining the genetic information
Advantages of sexual reproduction?
- Allows for evolution due to the genetic variability
- Can support the long term survival of a species
What is sexual reproduction?
Sexual reproduction is the fusion of 2 sex cells which makes a genetically unique offspring. This is done in 2 steps:
- The 2 sex cells joining to form a zygote, the first cell of a genetically unique individual through fertilization
- The formation of a haploid cell or gamete which contains genetic information from both parents
What are some modes of sexual reproduction with examples?
- External fertilization: parrot fish have egg cells that are layed and sperm cells fall on it
- Internal fertilization: Humans (most mammals)
How many chromosomes is in the cell during Meiosis 1 Prophase 1?
- Diploid cell containing 23 pairs of homologous chromosomes
What is meiosis?
A special type of cell division similar to mitosis. Present in organism that sexually reproduce and is the process that makes the gametes (sperm and egg cells) for sexual reproduction.
Difference between Mitosis and Meiosis?
- Mitosis has the same number of chromosomes in each generation (from parent cell to daughter cell)
- Meiosis starts with a diploid cell and ends with 4 haploid cells (chromosomes reduce by half by the end)
How does genetic variation occur in Meiosis
- The combination of two gamete cells each containing a complete set of DNA (one from each parent which contains one version of each gene) creating homologous chromosomes
- Genetic variation occurs during prophase 1 when homologous pairs crossover
- In metaphase 1 and 2 when chromosomes randomly pick which side to go to
Recite Meiosis for human sperm and egg cells
What is the production of sex cells?
The production of sex cells is called gametogenesis whcih is done through meiosis. In humans there are 2 types: spermatogenesis (1 diploid cell to 4 sperm cells) and oogenesis (1 diploid cell to 1 ovum and 3 polar bodies).
