Final Exam Flashcards
What is the process of producing egg and sperm cells?
Gametogenesis
In egg cells and sperm cells the chromosomes are located in what organelle of the cell?
Nucleus
What is it when a sperm cell from a male and an egg cell from a female unite to form a single cell called a zygote?
Fertilization
What is a zygote?
A diploid cell resulting from the fusion of two haploid gametes
How does a zygote divide?
Mitosis
What are the two types of chromosomes in a man?
X and Y
What are the types of chromosomes involved in sex determination?
Sex chromosomes
What are the two types of sex chromosomes?
Egg (X)
Sperm (X or Y)
How many sets of chromosomes are there in a human somatic cell?
23
How many chromosomes are there in a somatic cell?
How many from the father?
How many from the mother?
46
23
23
Of the 46 chromosomes in humans how many are autosomes?
How many are sex chromosomes?
44
2
How many sets of chromosomes are there in a human gamete?
23
How many autosomes are there in sperm and eggs cells? What about sex chromosomes?
22
1
How 44+XX zygote produced?
Egg: 22+X
Sperm: 22+X
How is a 44+XY zygote produced?
Egg: 22+X
Sperm: 22+Y
Reduction division in which the number of chromosomes per cell is _____.
Cut in half
Meiosis involves _____ divisions producing a total of _____ daughter cells.
Two
4
Meiosis occurs in what organ in females? What is the process called?
Ovaries
Oogenesis
Meiosis occurs in what organ in males? What is the process called?
Testes
Spermatogenesis
The cells in the ovary that are destined to become egg cells are called _____.
Are they diploid or haploid?
How many chromosomes are there?
Primary oocyte
Diploid
46
When does meiosis I occur in females?
Embryonic development
When does meiosis II occur?
Fertilization
The cells in the testes that are destined to become sperm cells are called _____.
Are they diploid or haploid?
How many chromosomes are there?
Primary sperm
Diploid
46
What stage precedes meiosis I?
What events occur during this stage?
Interphase
Growth
DNA synthesis
Etc
What are the four phases of meiosis I?
Prophase I
Metaphase I
Anaphase I
Telophase I
Cytokinesis
What are the four phases of meiosis II?
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesis
What is a pair of homologous chromosomes?
One member is obtained from the mother and the other from the father
Same size and shape
What are the events in prophase I?
Chromosomes coil tighter
Synapsis
Crossing over
What is crossing over in meiosis I?
Occurs during prophase I when homologous chromosomes pair up and exchange genetic material
What is chiasma?
X shaped regions where crossing over occured
Crossing over in meiosis I increases the ______ of the gametes.
Genetic variability
What are the events in metaphase I?
Tetrads line up at the metaphase plate
What is a tetrad?
A four part structure that consists of two homologous chromosomes, each composed of two identical chromatids
What separates in anaphase I?
Homologous chromosomes
What are the events in telophase I?
Each half of the cell has a haploid set of chromosomes.
Cytokinesis usually occurs simultaneously, forming two haploid daughter cells
What are the events in prophase II?
Spindle apparatus forms chromosomes (still composed of two chromatids).
Moves towards metaphase plate
What are the events in metaphase II?
Sister chromatids are arranged at the metaphase plate.
What separates in anaphase II?
Sister chromatids
What are the events in telophase II?
Chromosomes arrive at opposite poles
Nuclei forms and chromosomes begin decondensing
What are the four unique events to meiosis?
Crossing over
Synapsis (pairing homologues)
Sister chromatids remain attached during anaphase
Suppression of DNA replication during interphase
1 parent = 4 daughter
N=2n
1st meiosis
2nd meiosis
2n
n n
n n n n
Starting with 48 chromosomes (2n). How many in meiosis I and II?
24 and 24
Crossing over occurs in homologous _____.
Non sister chromatids
Crossing over occurs where on a chromosome?
Only the tip not middle
What are recombinant chromosomes?
Crossed over
What does 3 tetrads equal?
6 chromosomes= 12 chromatids
The segregation of the pair of alleles corresponds to the separation of _____ which occurs during _____ of meiosis 1.
Homologous chromosomes
Anaphase 1
When Mendel crossed contrasting, true breeding white and purple flowered pea plants all of the F1 hybrids were _____.
Purple
When Mendel crossed the F1 hybrids, many of the F2 plants had _____ flowers but some had _____ flowers.
Purple
White
The F1 hybrids had the recessive allele, but why were all of the F1 plants purple?
The dominant allele (purple) masked the recessive recessive allele (white).
Was the factor for white flowers diluted or destroyed in the F1 offspring? Explain.
No, because the gene was still there and it was just hidden by the dominant allele.
Mendel discovered a ratio of _____ in the _____ generation.
3 purple : 1 white
F2
What are the possible genotypes of the individual with a dominant phenotype?
AA or Aa
What will be done to know if the individual is homozygous or heterozygous dominant?
A test cross is performed