Download Biology – Study Guide – Meiosis and Genetics

Biology – Study Guide – Meiosis and Genetics
Meiosis
1) Asexual reproduction produces offspring that are __IDENTICAL__ to their parents. Sexual reproduction
produces offspring that are __DIFFERENT__ from their parents.
2) Meiosis is a process of __SEXUAL___ reproduction.
3) Name and draw the phases of Meiosis (2 divisions).
4) Meiosis occurs in _TWO__ cell divisions, the process _HALVES__ the number of chromosomes from
_DIPLOID__ to _HAPLOID__
5) Meiosis produces __GAMETES__ (sperm and egg)
6) What is crossing over? When DNA is transferred from one homologous chromosome to another.
When does it take place? During Meiosis I – usually Prophase I
7) What are homologous chromosomes? A pair of sister chromatids, one maternal and one paternal
8) When do homologous pairs of chromosomes align? Metaphase I of Meiosis
When do they separate? Anaphase I
9) What is the difference between a diploid cell to a haploid cell.
Haploid – (n) 23 chromosomes (gametes formed through Meiosis)
Diploid- (2n) double, 46 chromosomes (somatic cells formed through Mitosis)
10) What is a somatic cell? A body cell (skin, bone, nerve, etc)
How many chromosomes do human somatic cells have? 46 chromosomes
Are they haploid or diploid? diploid
11) What is a gamete? A sex cell (sperm or egg)
How many chromosomes do human gametes have? 23 chromosomes
Are they haploid or diploid? haploid
12) What is the male gamete called? sperm
What is the female gamete called? egg
13) What is fertilization? Sperm meets egg to create a zygote (23 + 23 = 46 chromosomes)
Is this a process of asexual reproduction or sexual reproduction? Sexual
14) What is a zygote? The cell formed from fertilization (sperm + egg) it will eventually mature into a fetus
15) What is an autosome? A chromosome that codes for body cells and traits (Pairs #1-22)
16) What is a sex chromosome? A chromosome that codes for sexual characteristics (Pair #23)
What are the sex chromosomes of a male? XY
What are the sex chromosomes of a female? XX
(Y chromosome comes from the father)
17) Compare and contrast Meiosis and Mitosis
Mitosis
Meiosis
Forms 2 somatic (body) cells that are clones
Forms 4 gametes that are genetically different
Forms Diploid cells – 46 chromosomes
Forms Haploid cells – 23 chromosomes
One cell division (PMAT)
Two cell divisions (Meiosis I and II)
Sister chromatids separate
Homologous pairs separate (Meiosis I)
Sister Chromatids separate (Meiosis II)
Mutations affect body cells
Mutations affect offspring
Genetically identical offspring
Crossing over occurs during Prophase I
Genetics
1) The passing of characteristics from parent to offspring is called _HEREDITY___
2) The study of the inheritance of traits is called _GENETICS___
3) The “Father of Genetics” is __MENDEL__ (the man who tested on Pea plants)
4) PUNNETT SQUARE__ is the tool used to predict the possible offspring from crosses?
5) Define allele = different forms of a gene that can create different characteristics. (Ex. T-tall t-short)
6) What does the Law of Segregation state?
During fertilization, each parent donates ONE allele to the offspring (explains how alleles are separated
during Meiosis)
7) What does the Law of Independent Assortment state?
Genes that are on separate chromosomes are distributed (passed down) independently from one another
8) In the Law of Dominance it states that a __DOMINANT (uppercase)__ allele will express the dominant trait
and that a __RECESSIVE (lowercase)__ allele may be masked (or hidden).
9) What is a genotype? The pair of genes that code for a trait. Ex. Tt or BB or dd
10) What is a phenotype? The physical expression of a trait. Ex. Tall, Brown eyes, wrinkled
11) What are homozygous alleles? BB or bb (same)
also called Purebred
12) What are heterozygous alleles? Bb
also called Hybrid or Carrier
(different)
13) What causes Down Syndrome? an extra chromosome (also called Trisomy 21)
14) What is the difference between Incomplete dominance and Codominance?
Incomplete Dominance: neither gene is dominant, a third phenotype (mixture) will show
Ex. RR=red
WW=white
RW=pink
Codominance: both genes display dominance, a third phenotype (both) will show
Ex. RR=red
WW=white
RW= red and white
15) What is an example of a human trait inherited by polygenic inheritance?
Traits that are controlled by 2 or more genes. Ex. hair color, eye color, skin color
16) What is an example of a human trait inherited through multiple alleles?
A trait that has 2 or more possible alleles. Ex. Blood Type (3 alleles) IA, IB, or i
17) What is an example of a human trait that is sex-linked?
A trait that is connected to a gene on the sex chromosome.
Ex. Colorblindess is recessive and linked to the X chromosome (seen more often in males)
Female = XCXC and XCXc (not colorblind)
Male = XCY (not colorblind)
XcXc (colorblind)
XcY (colorblind)
18) What is a pedigree? Review the examples we labeled in class.
A chart showing a pattern of inheritance.
Squares = males
Circles= females
Shaded=affected (has the trait)
The 1st chart to the right shows a pedigree for a recessive
trait. (It is not seen in every generation)
The pedigree to the left shows a dominant trait.
The trait is seen in all 3 generations.
The pedigree to the right shows a sex linked traits.
The individuals affected are mostly male.
You must be able to complete a Punnett Square and report the Genotype and Phenotype probability of the
offspring.
18.)The genes for hair type are H = curly h = straight. Cross a heterozygous male with a homozygous recessive
female.
The ratio of curly haired offspring to straight haired offspring would be 1:1 or 50% curly, 50%straight
19.) Red and blue flowers show Incomplete Dominance. Cross a homozygous dominant red flower with a
homozygous dominant blue flower. (R-red and B-Blue)
The offspring would be 100% Purple a ratio of 0:4:0
20.) In humans colorblindness (b) is an example of a Sex-linked recessive trait. In this problem, a male with
color blindness marries a female who is not colorblind but carries the (b) allele.
Males : Ratio of 1:1 , 50% colorblind XbY and 50% not colorblind XBY
Females: Ratio of 1:1
50% colorblind XbXb, 50% not colorblind XBXb