Chapter 8, 9, 10 - Bio Exam 3

What are the main phases of the eukaryotic cell cycle?

Interphase, prophase, metaphase, anaphase, telophase

What happens during interphase?

G1, S, G2

What happens during prophase in mitosis?

chromatin condense into chromosomes; spindle starts to forms; nuclear envelope dissolves

What happens during metaphase in mitosis?

the homologous chromosomes line up along the metaphase plate

What happens during anaphase in mitosis?

centromere splits and sister chromatids move to opposite poles

What happens during telophase in mitosis?

nuclear envelope forms; spindle dissolves; chromosomes go back to chromatin; cytokinesis starts

How do the interphase stages prepare for cell division?

G1 is the main growth stage; S is the DNA synthesis stage and centrioles replicate; G2 makes the last modifications to prepare for cell division

How does cytokinesis differ between plant and animal cells?

animal cells form a cleavage furrow that forms from the outside that pinches off; plant cells have a cell wall that needs a cell plate to divide from inside the cell 

What is the role of checkpoints in the cell cycle, and what happens when they fail?

They are to make sure a cell has no abnormalities and is safe to carry out cell division. If they fail they go through apoptosis.

What are proto-oncogenes and tumor suppressor genes?

Proto-oncogenes are what tell the cell to divide and can code for growth factors; tumor suppressor genes are what tell the cell to stop dividing, repair, or go through apoptosis

How do mutations in these genes contribute to cancer?

cells could divide uncontrollably; lead to mutations in genes

How do mutations affect proteins and cell cycle regulation

proteins are coded for genes. and when mutations occur proteins do not work anymore and cannot carry out their functions

What types of human cells divide rapidly, and why?

hair follicles, skin cells, fetal, lining digestive tract, RBc , WBC, etc. This is because these cells are constantly growing or can regenerate.

What is the structure of DNA?

deoxyribose sugar, phosphate, base (thymine), double helix

What is the structure of RNA

ribose sugar, phosphate, base (uracil), single string

What are the components of a nucleotide, and how do they assemble into DNA?

A sugar, phosphate, and a base. Nucleotides link together, with the phosphate group of one nucleotide forming a covalent bong with a sugar. 2 stands come together to form the double helix. Stands pair with A, T and C

What is the purpose of meiosis, and how does it differ from mitosis?

To produce sex cells; there is 1 duplication, and 2 divisions

What are the major phases of meiosis I and II?

Meiosis I: Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I; Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II

What happens during interphase?

DNA synthesis, centrosomes duplicate and cell growth

What happens during prophase I?

homologous chromosomes pair up and form a tetrad; crossing over happens; nuclear membrane starts to disappear; spindle forms

What happens during metaphase I?

homologous chromosomes line up in pairs along the metaphase plate; independent assortment

Anaphase I

homologous chromosomes are pulled to oppositie poles

Telophase I

homologous chromosomes are fully separated; nuclear envelope reappears; spindle disappears; 2 haploid cells; cytokinesis

What happens during prophase II?

chromosomes condensed into chromatin; nuclear envelope breaks down; spins forms

Metaphase II

chromosomes line up along the metaphase plate

Anaphase II

centromere splits and sister chromatids separate to opposite poles

Telophase

produces 4 haploid cells; nuclear envelop develops; spindle disappears; cytokinesis starts

What events contribute to genetic variation in sexually reproducing organisms?

crossing over - chromosomes trade genetic information

independent assortment - homologous chromosomes line up independently of each other

What is the difference between diploid and haploid cells?  Where are each found?  At what point in meiosis is the cell haploid/diploid?How does nondisjunction lead to chromosomal abnormalities?

diploid cells are found in somatic cells; and are genetically identical to their parent and each other; haploid cells are found in reproductive cells; have half the number of chromosomes than the parent and are genetically different from the parent and each other. In meiosis the cell is haploid after meiosis I

How does nondisjunction lead to chromosomal abnormalities?

It is the failure of either homologous chromosomes or sister chromatids to separate normally during division.

This results in an abnormal number of chromosomes in the daughter cells causing down syndrome

Define aneuploidy and what are its consequences?

Having too many or too few chromosomes; Causes miscarriage; Or causes disorders if there’s an additional 13, 18 or 21

What are the differences between prophase I and prophase II?

crossing over only happens in prophase I

When given a karyotype, be able to identify the missing/additional chromosome.  How would this have formed through the process of meiosis

Malfunction during anaphase 1 or anaphase 2 (nondisjunction

What were Mendel’s key contributions to genetics?

theory of heredity; law of segregation; independent assortment

What are dominant and recessive traits, and how do they appear in offspring

1. Dominant traits

   1. More likely to present, and if present it is visibly expresses.

   2. Homozygous dominant or heterozygous

2. Recessive traits

   1. Less likely to be expressed.

Homozygous recessive

How do genotypes and phenotypes differ?

makeup vs looks

define a testcross, how is it used for genotype

to see an individual’s actual genetic composition; you are able to see what an individual is through the offspring it produces with a homozygous recessive parent 

What are Mendel’s laws of segregation and independent assortment?

1. Law of segregation

   1. Two alleles of a trait separate during meiosis.

2. Law of independent assortment

   1. Chromosomes pair up differently every time and assort independently of one another

How do monohybrid and dihybrid crosses differ? What patterns do they reveal?

1. Monohybrid is the possibilities of a singular trait.

   1. Reveals basic inheritance and dominance.

2. Dihybrid is the possibilities of 2 traits at once.

   1. Law of independent assortment

   2. How different genes assort differently and independent from each other.

What is incomplete dominance? How does it differ from complete dominance?

1. Incomplete is when 2 traits mix and neither one nor the other is showing.

2. The ability of 2 alleles to produce a heterozygous phenotype that is different from the homozygous phenotypes.

1. What is codominance? How does it apply to human blood types?

1. Codominance is when some of one trait shows and some of the other trait shows.

2. Effects of both alleles are present in the phenotype of a heterozygote.

3. 2 alleles of a given gene have different phenotypic effects, with both effects manifesting in organisms that are heterozygous for the gene.

4. Two different alleles for a gene are inherited, and both are fully and equally expressed in the offspring. A and B alleles are codominant over each other, but both are dominant over the O allele.  

What is polygenic inheritance, and how does it explain traits like height?

1. Multiple genes control this trait.

2. It may produce a continuous rang of phenotypic values rather than a this or that value.

3. It explains traits like height because there is continuous variation because there is more than one gene controlling this trait so variation travels along a continuum.

How do pedigrees help us understand inheritance patterns?

The patterns of inheritance observed in family histories. Used to determine the mode of inheritance of a particular trait.

How can you distinguish between autosomal dominant, autosomal recessive, and X-linked inheritance in a pedigree?

1. Autosomal dominant

   1. For an individual to be affected by the disease only need ONE upper case letter to have the disease

   2. appears in every generation

2. Autosomal recessive

   1. An individual to be affected they need both lower case letters to have disease

   2. is in every other generation

3. X-linked inheritance

   1. Affects more males than females

   2. If the male is affected then no daughters will be

How do sex-linked traits differ from autosomal traits in inheritance?

They affect males more than females