Exam 2 Flashcards
Define Phenotype
Physical expression of genes
Dominate and Recessive versions
Define Genotype
Genes present in an individual
Alleles of a gene (AA, Aa, aa)
Define
- Homozygous Dominate
- Homozygous Recessive
- Heteozygous
- Homozygous Dominate: AA
- Homozygous Recessive: aa
- Heteozygous: Aa
Who is Gregor Mendel? What did he discover?
Father of genetics
Established fundamental laws of heredity
Came up the concept of alleles: different versions of genes
An organism has two verions of every gene one from each parent creating: AA, Aa, or aa
Define the Law of Segregation
During gamete production (egg/sperm) when the alleles are copied the are separated so that a parent can only give one allele.
Instead of mom giving Aa she only gives a
Define the Law of Independent assortment
Alleles are copied independently
Copying an A from Aa does change the likely hood of getting another A or getting an a instead the next time
Define Linked Genes
Genes close together on a chromosome so the are more likely to inherited together instead of being seperated
Define Dominate gene
Strong Phenotype: Will be expressed more
Define Recessive gene
Weak phenotype: Easily masked or hidden
Define Co-dominance
Both the phenotypes of the alleles express themselves creating stark contrasts
Example: A red flower and a white flower creating a red and white flower
Define incomplete dominance
Phenotypes get mixed like paint
Example: A red flower and a white flower creating a pink flower
Define Law of Heredity
Unchanging Hereditary elements undergo segregation and independent assortment.
Elements are passed on unchanged to offspring leading to finite number of variations
Define Dihybrid cross
Crossing two homologous parents and tracking 2 geneotypes
Cell Cycle: what are 4 phases?
- Mitosis: Cell splitting
- Growth 1: Normal growth of organelles and such
- Synthesis: DNA replication
- Growth 2: Growth for division
Mitosis: what are the 5 phases?
Prophase: Single chromosomes copy making sister chromotids then they attach themselves with centromeres in the middle which create the x looking chromosome.
Spindle fibers/Mitotic spindle form
Nuclear membrane dissolves
Metaphase: Chromosomes line up in the middle of the cell
Spindle attaches to the centromere
Anaphase: The sister chromotids of the chromosomes are split apart and retracted to the end of the cell (like spider-man webbing)
Telophase: two Nuclear Membrane form around the new groups of DNA
Cytokinesis: Cell begins to divide itself
Define Non-disjuntion Events
DNA fails to separate properly
Often Issues during Anaphase I or II because the spindle could attach improperly missing a chromosome for one side and grabbing an extra on the other side
Examples
- Patau Syndrome: Trisomy (extra 13th chromosomes)
- Edward Syndrome: Trisomy (extra 18th chromosome)
- Down syndrome: Trisomy (extra 21st chromosome
- Klinefelter syndrome: Momosomy (extra x chromosome in males)
- Turner syndrome: Momosomy (missing X chromosome in females)
- Triple x: Extra x for females
- XYY: an extra Y in males
Define Meiosis
Special type of Mitosis for gamete cells (egg and sperm cells)
Duplication of the chromosomes before division starts and goes through the two rounds of cell divison (Meiosis 1 and 2)
Main Difference between Mitosis and Meiosis
Metaphase and Anaphase
Meiosis will serparate chromosomes and then chromatids
Mitosis starts will seperating the chromotids
Define crossing over
Homologous chromosomes pair up and can swap/exechane genetic info with each other
Define Ploidy
Number of chromosome SETS in a cell
triploid cell has 3 chromosomes for each type/nmber
Diploid cell has 2 chromosomes for each type/number
Haploid cell has 1 chromosome for each type/number
Ploidy descriptions: with n count
NumberOfCopies * number of unqiue chromosomes = total number of chromosomes
Example:
People are 2n = 46: 2 copies of 23 unique types creating 46 total chromosomes
4n = 12: 4 copies of 3 unique types creating 12 total chromosomes
Facts about Spermatogenesis
Happens in testicles or testes
Collected in epididymis then transported to the body using various tubes
Other glands join
100-200 million sperm are made by one man in a single day
64 days to mature sperm
Facts about Ovulation/Oogenesis
Oogonium cells: Diploid cells that make eggs, preform all the mitosis they will ever before long before the female was ever born
They are arrested/stuck in prophase 1 until puberty
Once a month one is chosen to finish meiosis 1 then stops and waits to be fertilized in order to move forward onto meiosis 2
While waiting at the end of meiosis 1 2 cells are waiting: Polar body and a full egg cell with all organelles
Progesterone is produced to keep the uterine from shedding
If egg is fertilized it moves on to meiosis 2
If not the progesterone hormone drops and lining is shed (Period)
How do miscarriages work?
Most miscarriages are Polar bodies getting fertilized instead of the egg. Since the polar body has no organelles it can’t function or live, but creates all the hormones associated with pregnancy
Define Asexual reproduction
Offspring can arise from a single oranges and inherit the genes of that parent only
No fusion of gametes
Almost never changes number of chromosomes
Example: Most bacteria and single celled organisms
Define Fragmentation
Type of Asexual reproduction
Cloning where an organism splits into fragments and then each fragment develops into mature fully grown individuals that are clones
Ex: sear stars, molds, Cyanobacteria, lichen
Define budding
Type of Asexual reproduction
A new organism develops from an outgrowth or bud due to cell division at one particualr site.
The new organism remains attached as it grows seperating from the parent organism only when it is mature, leaving behind scar tissue
Examples: Corals, flatworms, some sea sponges
Define Binary Fission
Type of Asexual reproduction
For prokaryotic cells
DNA replication and segregation occur simultaneously: DNA molecule divides and forms two seperate DNA molecules (no centromere)
DNA is moved to opposite end of the cell
Cell divides
Define Parthenogenesis
Offspring develop from unfertilized eggs
Ex: anthropods, notifiers, fish, amphibians, birds, reptiles
(Note: these all lay eggs, mammals can’t do parthenogenesis)
How are our genetypes expressed into phenotypes?
Protein creation!
Proteins are created from DNA and RNA
What is the Central Dogma of Molecular biology for genes?
DNA is transcibed into RNA
RNA translates and makes proteins/polpeptide chains
DNA -> RNA -> Protein
What is the general form/shape of DNA
Double Helix
What is the basic unit/monomer of DNA? What types exist?
Nucleotides: 4 types
Adenine
Cytosine
Guanine
Thymine
Uracil is a pryimidine similar to Thymine and is RNA’s replacement/version
What 3 molecules make up a nucleotide?
A Phosphase residue
A sugar (deoxyribose)
A nitrogenous base: adenine, guanine, etc.
What are anti-paralell strands of DNA?
DNA strands that are opposites of each-other in such a way that bringing opposite strands together fit together forming a double strand which then twists into a double helix shape
How do nucleotides pair up?
A-T or U for RNA
G-C
Each pair contains one purine and one pyrimidine