Unit 2 Final Flashcards
Gamete
A sex or reproductive germ cell that can unite with the opposite sec to form a zygote
Autosome
Any chromosome that is not a sex cell
Allele
A version or variation of a gene with the offspring inheriting one from each parent
Genotype
An organisms genetic make up
(Combination of alleles)
Homozygous
Having two identical alleles
HH hh
Dominant
Only one Allele is needed to overshadow the recessive for the trait to show up
Phenotype
What organism looks(traits they possess)
Heterozygous
Having two different alleles
Hh
Recessive
Only expressed when someone inherit two copies of a lowercase letter
Which parent dictates the child’s sex
The father because he posses an X and a Y chromosome while the mother can only contribute an X so if half of each parent gets passed down the father could pass on his y being a male or an x being female
Possible genotypes for blood types
Type A
Ia Ia, la lo
Type b
Ib lb, lb lo
Type AB
Ia lb
Type O
Io lo
Difference between chromosome and gene
Chromosome – thread, like made up of DNA and proteins contains genes 46 of them organized into 23 pairs
Gene– segments of DNA carrying genetic codes, located on chromosomes, determine traits and characteristics
Purpose of meiosis
Because if we didn’t reduce the number of chromosomes before sexual reproduction our chromosome numbers would keep duplicating and we wouldn’t survive
If we kept 46 and mated with another 46 we would have 92 which isn’t a human more like an aquatic rat
How many chromosomes are in the beginning of meiosis
46
How many chromosomes are at the end of meiosis
23
How do chromosomes divide through phase 1 and phase 2 of meiosis
Anaphase 1 – homologous chromosomes separate, pulled to opposite polls
Anaphase 2- sister, chromatids separate, and moved to opposite poles of the cell
Nondisjunction
Cause an abnormal amount of chromosomes in the body because a homologous pair fails to separate during anaphase so they both pass to the same daughter cell.
Baby has the wrong chromosome number
Trisomy – cells have three copies of a chromosome
Monosomy – cells have only one copy of a chromosome
Crossing over
Homologous chromosomes cross over and exchange genetic information during prophase 1 this causes more genetic diversity in the offspring
Steps of meiosis
Interphase 1-
Genetic material is in the form of chromatin when cell division is about to occur the DNA replicates (1 strand to 2 strands)
Prophase 1-
Chromosomes appear short and thick. Each chromosome has two chromatids homologous chromosomes come together in pairs each pair has four chromosomes.
Tetrad, intertwine and crossover, allowing genetic information to be exchanged
Spindle fibre begin to form nuclear membrane breakdown
Metaphase 1-
Tries lineup in the middle of the cell central region of the tetrads become attached to the centriole which are attached to the spindle fibres
Crossing over is still evident
Anaphase 1-
Homologous chromosomes of each cell are pulled to opposite poles by spindle fibres attached to the centromer each daughter cell gets one of each homologous pair
Telophase 1-
Spindle fibres are broken up new nuclear membranes, form chromosomes uncoil
Cytokinesis-
Two cells results chromosomes are double stranded as they fade from view
Interkenises- similar to interphase except no dna replication occurs because the chromosomes are already double stranded
Prophase 2-
Chromosomes(double stranded) become visible and compact crossing over does not occur in the second stage nuclear membrane begins to break down spindle fibres begin to form
Metaphase 2-
Chromosomes lineup in the centre of the cell, spinal fibres are attached at the central region, and into the central at the polls chromosomes are paired rather than in tetrads as in metaphase one
Anaphase 2-
Double stranded, chromosome, separate, and migrate towards the polls with the chromatids trailing behind the centromeres
Telophase 2-
Cell division is complete for new daughter cells have been produced each with different gene combinations from any of its sister cells
Purpose of a karyotype
It’s an organized profile of a persons, chromosome, showing the number and size of the chromosomes
This can help determine if there are any genetic or health issues
How many chromosomes do humans have
46
Karyotypes
Down syndrome – one cell has 2 21st chromosomes instead of one so the resulting fertilized egg has 3 21st chromosomes hence the name trisomy 21
Either male or female
Have 47 chromosomes instead of 46
Knows, have low bridge large ton hands are short and broad, short body and deformed heart mental disability
Edward syndrome (47, Trisomy 18)
Abnormalities of the internal organs, such as heart
Head is small and abnormally shaped
Less than 5% survive less than one year
Severe intellectual disability, found more often in females
Patua syndrome(47, trisomy 13)
Extra copy of the 13th chromosome
Average survival 2.5 days
Brain malformations, mental disability, and heart problems
Sex, chromosome abnormalities meaning wrong amount in sex chromosomes
Klinefelters syndrome
XXY male
Have male sex organs, but are sterile
Feminine characteristics, some breast development, lack of facial hair
Tall
Normal intelligence
High-pitched voice
Jacob syndrome male
YY male
Extra Y chromosome
Slightly taller than average
Normal intelligence, slight learning disabilities
Delayed emotional maturity
Normal sexual development
Turner syndrome
Monosomy X or X0
Very degree of affects
Webbed neck
Short stature
Sterile
Autosomal recessive
Happens in both sexes with equal frequency
Trait can skip gens
Affected offspring born to unaffected parents
Autosomal dominant
Both parents transmit it
Unshaded individuals are homozygous recessive
Does not skip gens
When one parent is affected, and the others unaffected, approximately 1/2 of the offspring will be affected
Unaffected parents do not transmit the trait
