Bio 11 Flashcards
fertilization
when sperm and egg cells join in sexual reproduction
Gregor Mendel
He was a monk who worked with peas in the 1800s to create the foundation of genetics
true breeding
When self pollinated, produced the same exact trait every time
-means that the genotype is homozygous
cross pollination
pollinating one pea plant with another
hybrid
a cross between two different traits
- genotype is heterozygous
when plants with different traits are cross pollinated, in most cases …..
the traits didn’t “mix”, they chose one or the other
Principle of Dominance
certain alleles for a gene are either DOMINANT or RECESSIVE
-(there are some exceptions to this rule- chapter 11.3)
segregation
gamtetes are formed during meiosis- the different alleles separate separately
probability
likely hood an event would occur
punnet square
shows likely outcomes of a genetic cross
how do you use a punnet square
you put the genotypes of each parent around the edges and combine one allele with another in each square
Genotype
genetic make up
phenotype
physical outcome of genotype
-based on if gene is dominant of not
homozygous vs, heterozygous
same or different alleles
segregation and punnet squares
because alleles segregate separately, the different alleles that are passed on can be passed on in any way. That is why punnet squares work.
Independent Assortment
Segregation happens independently from other genes
- EX: one pair of alleles segregation doesn’t effect another pair
Dihybrid cross
a punnet square with two hybrid parents with two genes each
-EX: BbRr each,
PHENOTYPES!!
9 outcomes- B_,R_
3 outcomes- bb,R_
3 outcomes- B_, rr
1 outcome- bb,rr
What are mendels 4 principles
- genes determine biological characteristics
- alleles are dominant or recessive
- there are 2 alleles for each gene
- independent assortment- alleles from different genes segregate separate
True or False- Mendels Principles are always true
FALSE!!!
which of Mendel’s principles are not always true
- multiple alleles can be dominant, both alleles may be not dominant
- there can be more than 2 alleles
- more than one gene can code for one trait
Incomplete Dominance
Alleles are not always completely dominant
- the alleles mix together (red + white = pink)
Codominance
More than one allele is dominant
- the alleles splotch together
Multiple Alleles
having 3 or more alleles for one gene, more than just two options
- no extra results, just less high probability for each one
Polygenic trait
Multiple genes go into one trait
- hair color is effected by multiple different factors
Rules of genetics apply to all organisms (t or f)
TRUE!!
pedigree
map of family history homing in on a certain trait often to understand if it was recesssive or sex linked
What are some occurrences in a pedigree that could point to either sex linked or recessive traits
if the gene skips a generation- recessive
if the gene is found in almost only male- sex linked
How is the chromosome number passed on through generations
Each generation has the same number of chromosomes as the lastd
diploid
When there are two of each chromosome, (46 chromosomes)
haploid
a cell with only one of each chromosome (23 chromosomes)
homologous
when there are two of each chromosome- this is what most cells (diploids) have
Meiosis
The division of cells into 4 haploid (gametes) cells
Meiosis 1
the first part of meiosis
-diploid cell with four chromatids of each chromosome number
- ends with two haploid cells with two chromatids per chromosomes
Meiosis 11
the second part of meiosis resembling mitosis with 23 chromosomes instead of 46
phases of meiosis 1
- prophase, spindle forms, nuclear envelopes dissolve, chromosomes of the same number line up next to each other ( forming tetrads) and cross over
- metaphase, tetrads line up in center of cell
- anaphase, chromosomes are pulled apart from each other (chromatids are still together)
- telophase- cell splits into two haploids
phases of meiosis 11
EXACTLY THE SAME AS MITOSIS
polar bodies
3 of the four gametes produced by meiosis in females are polar bodies, one large one is an egg cell
Genes are linked together along chromosomes, their placement can be determined by …
Gene maps created from the way genes split up from each other during crossing over.
tetrad
when chromosomes meet up in the middle of a cell during meta-phase 1
