Biology exam 2

Prophase

Chromosomes condense and pair up

Prometaphase

spindles attach to center of chromosome

spindle

micrtubules that seperate chromosomes during meiosis

metaphase

chromosomes lines up in center of cell

anaphase

chromsomes separate apart towards edges - sister chromatids do not

telophase

cytokinsis occurs - break apart to create two seperate cells, now have own chromosomes

process of mitosis

starts with prophase, ends with telophase

meiosis

goes through mitosis process, and then does process again -

chromosome

condensed / a single long DNA double helix packaged with proteins

what is the central dogma

DNA makes RNA makes proteins

What is a gene?

A gene is a DNA sequence that codes for proteins

what is an Allele?

Different versions of gene, (hair color) (skin tone)

eukaryotic

animal + human cell

plant cell

makes up plants

prokaryotic cell

bacteria

Using the central dogma, how could the alleles a person has for the ABO blood type lead to them having type AB blood?

You inherit one A allele and one B allele. Each one makes its own enzyme. The enzymes put A and B sugar tags on your red blood cells. Both tags = type AB.

Is the karyotype shown (chromosomes 1-22 plus XY, in matching pairs) from a haploid or diploid organism, and how can you tell?

Diploid, because the chromosomes come in matching pairs (two copies of each, one from each parent)

What is the outcome (product) of mitosis?

Two genetically identical daughter cells with the same number of chromosomes as the parent cell

What does meiosis do that makes sexual reproduction possible?

It starts with a diploid cell and makes haploid cells, so that two gametes can combine into a diploid offspring

What happens during prophase I of meiosis?

Chromosomes condense and homologous chromosomes pair up

What does it mean to be homozygous dominant?

Two alleles associated with the dominant trait (for example, EE)

What is a pedigree useful for?

Determining whether a trait is heritable, its model of inheritance, and individuals' possible genotypes

Sickle-cell anemia is a recessive Mendelian trait. Dan is heterozygous for the β globin gene and Asma is homozygous recessive. What is the probability that their first child will have sickle-cell anemia?

1/2

How does aneuploidy occur?

Chromosomes or chromatids failing to separate properly during meiosis, giving gametes with extra or missing chromosomes

If nondisjunction happens in meiosis I, what are the four resulting gametes?

Two gametes with n+1 and two gametes with n-1 (all four abnormal)

If nondisjunction happens in meiosis II, what are the four resulting gametes?

One n+1 gamete, one n-1 gamete, and two normal (n) gametes

if an n-1 gamete is fertilized by a normal gamete. What is the chromosome number of the zygote?

2n-1: the zygote is missing one chromosome (monosomy)

if an n+1 gamete is fertilized by a normal gamete. What is the chromosome number of the zygote?

2n+1: trisomy, with three copies of one chromosome

One homologous chromosome carries G and D, and the other carries g and d. Which combination of alleles could only be in a gamete together if crossing over occurred?

D and g