bio 161 exam 3

Eukaryotic chromosomes

Molecular composition includes DNA and histone proteins; chromatin is 40% DNA and 60% protein.

Nucleosomes

Structures that organize eukaryotic chromosomes, consisting of DNA wrapped around histones.

Centromeres

The part of a condensed chromosome that helps in spindle attachment.

Telomeres

The ends of chromosomes, important for stability.

Chromatin

The uncondensed form of chromosomes found in non-dividing cells.

Chromosome

The condensed form of chromatin seen in dividing cells.

Heterochromatin

Inactive, tightly packed form of chromatin.

Euchromatin

Active, loosely packed form of chromatin.

Drosophila polytene chromosomes

Giant chromosomes found in fruit fly salivary glands, used for gene mapping.

Karyotype

A chromosome chart used to detect number abnormalities, sex chromosomes, and genetic diseases.

Homologous chromosomes

Pairs of chromosomes with the same genes, one from each parent.

Phases of the cell cycle

Include Interphase (G1, S, G2), M phase (mitosis), and cytokinesis.

G1 phase

The phase of the cell cycle where the cell grows.

S phase

The phase of the cell cycle where DNA replication occurs.

G2 phase

The phase of the cell cycle where the cell prepares for division.

Importance of mitosis

Ensures growth, repair, and identical genetic information in diploid organisms.

Stages of mitosis

Include Prophase, Metaphase, Anaphase, and Telophase.

Spindle apparatus

Structure that moves chromosomes during mitosis.

Purpose of mitosis

Produces genetically identical daughter cells to maintain tissue and function.

Mitosis in animal cells

Characterized by the formation of a cleavage furrow.

Mitosis in plant cells

Characterized by the formation of a cell plate.

Cytokinesis

The division of cytoplasm to form two separate daughter cells.

Cell cycle control

Managed by checkpoints (G1/S, G2/M, spindle) that ensure proper division.

p53

A tumor suppressor protein that halts the cell cycle if DNA is damaged.

Proto-oncogenes

Genes that stimulate cell division; can lead to cancer when mutated.

Meiosis

Type of cell division essential for sexual reproduction, creating genetic diversity.

Haploid gametes

The cells formed by meiosis, which include egg and sperm.

Haploid vs Diploid

Haploid (n) has 1 set of chromosomes; Diploid (2n) has 2 sets.

Meiosis vs Mitosis

Meiosis involves 2 divisions and creates 4 genetically unique haploid cells.

Stages of Meiosis I

Include Prophase I, Metaphase I, Anaphase I, and Telophase I.

Stages of Meiosis II

Include Prophase II, Metaphase II, Anaphase II, and Telophase II.

Result of meiosis

Produces four haploid cells, each genetically different.

Synaptonemal complex

Holds homologs together during Prophase I.

Crossing over

Process where non-sister chromatids exchange genetic material, increasing variation.

Independent Assortment

Random alignment of chromosomes during Metaphase I, leading to genetic variation.

Spindle attachments in mitosis

Each chromatid attaches to opposite poles.

Spindle attachments in meiosis

Sister chromatids attach to the same pole in Meiosis I.

Sexual reproduction vs Asexual reproduction

Sexual reproduction leads to variation; Asexual reproduction yields identical offspring.

Advantages of sexual reproduction

Diversity is a major benefit.

Disadvantages of sexual reproduction

Requires more energy and a mate.

Impact of meiosis

Essential for producing diversity and aiding in evolution.

Mendel’s experiments

Studied pea plants and observed inheritance patterns leading to genetic laws.

Mendel’s success factors

Large sample sizes, controlled breeding, and quantitative data.

Mendel’s model vs Sutton’s theory

Mendel described inheritance; Sutton tied it to chromosome behavior in meiosis.

Phenotype

The observable traits of an organism.

Genotype

The genetic makeup of an organism.

Homozygous

Having two identical alleles for a trait.

Heterozygous

Having two different alleles for a trait.

Dominant

An allele that is expressed in the phenotype.

Recessive

An allele that is hidden in the phenotype.

Monohybrid cross

A genetic cross that examines the inheritance of a single trait.

Dihybrid cross

A genetic cross that examines the inheritance of two traits.

F2 phenotypic ratio of monohybrid cross

3:1 ratio.

F2 genotypic ratio of monohybrid cross

1:2:1 ratio.

Phenotypic ratio of dihybrid F2

9:3:3:1 ratio.

Test cross

Crossing an unknown genotype with a homozygous recessive to determine the unknown.

Segregation

The process during gamete formation where alleles separate.

Independent Assortment

The random distribution of alleles during gamete formation.

Incomplete dominance

An intermediate phenotype is expressed in offspring (e.g., red + white = pink).

Codominance

Both alleles are expressed simultaneously (e.g., AB blood type).

Pleiotropy

A single gene influences multiple traits.

Continuous variation

Traits that exhibit a range of phenotypes.

Environmental influence on phenotype

External factors can affect gene expression.

Epistasis

One gene can mask the expression of another gene.

Genetic factors and disease

Conditions like pleiotropy, incomplete dominance, and environmental influences affect diseases.

Inheritance patterns of genetic diseases

Includes autosomal dominant/recessive, X-linked dominant/recessive, and mitochondrial inheritance.

Pedigree chart

A diagram showing inheritance patterns across generations.

Mitochondrial and chloroplast contributions

Provide maternal inheritance and play roles in cellular energy.

Examples of genetic disorders

Sickle cell anemia, albinism, Down syndrome, etc.

Nondisjunction

The failure of chromosomes to separate properly in meiosis.

Disorders caused by nondisjunction

Examples include Turner’s syndrome (XO), Klinefelter’s syndrome (XXY), and Down syndrome (trisomy 21).

Genetic counseling

The process of assessing genetic risks in families, often using pedigree charts.

Prenatal screening techniques

Include Amniocentesis and Chorionic Villus Sampling (CVS).

How many chromosomes do people with Down syndrome have

People with Down syndrome typically have three copies of chromosome 21, resulting in a total of 47 chromosomes

How many chromosomes do women with turner syndrome have

Women with Turner syndrome typically have 45 chromosomes, with a missing X chromosome, resulting in a genotype of 45,X.

What is the sex chromosome for Turner syndrome

XO

How many chromosomes do men with Klinefelter syndrome have

47

What is the sex chromosome Klinefelter syndrome

XXY

How many chromosomes do men with jacob’s syndrome

47

What is the sex chromosome for jacob’s syndrome

XYY

How many chromosomes do women with Poly X syndrome have

47

What is the sex chromosome for Poly X

XXX

What goes on during prophase in meiosis

During prophase in meiosis, homologous chromosomes pair up and exchange genetic material through crossing over, while the nuclear envelope begins to break down.

What goes on during anaphase in meiosis

During anaphase in meiosis, sister chromatids are pulled apart to opposite poles of the cell, and the spindle fibers shorten, ensuring each new cell will receive an equal set of chromosomes.

What goes on during metaphase in meiosis

During metaphase in meiosis, homologous chromosomes line up at the metaphase plate, and spindle fibers attach to the kinetochores of each chromosome, preparing for separation.

What goes on during telophase in meiosis

During telophase in meiosis, the separated chromosomes reach the poles of the cell, the nuclear envelope reforms around each set of chromosomes, and the cell prepares for cytokinesis, which will divide the cytoplasm and complete the formation of two distinct daughter cells.

What goes on during interphase in meiosis

During interphase in meiosis, the cell undergoes growth and DNA replication, resulting in duplicated chromosomes, followed by preparation for the two meiotic divisions.

What goes on during cytokinesis in meiosis

Cytokinesis in meiosis occurs after telophase, where the cytoplasm divides, resulting in two daughter cells, each with half the original chromosome number.

What goes on during interphase in mitosis

During interphase in mitosis, the cell grows, replicates its DNA, and prepares for cell division by ensuring all necessary organelles are duplicated.

What goes on during prophase in mitosis

During prophase in mitosis, the chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the mitotic spindle begins to form, anchoring at the centrosomes.

What goes on during anaphase in mitosis

During anaphase in mitosis, the sister chromatids are pulled apart towards opposite poles of the cell as the spindle fibers shorten, ensuring that each daughter cell will receive an identical set of chromosomes.

What goes on during metaphase in mitosis

During metaphase in mitosis, the chromosomes align at the cell's equatorial plane, known as the metaphase plate, and the spindle fibers attach to the centromeres of each chromosome, ensuring proper distribution to the daughter cells.

What goes on during telophase in mitosis

During telophase in mitosis, the chromosomes begin to decondense back into chromatin, the nuclear envelope re-forms around each set of chromosomes, and the mitotic spindle disassembles, concluding the process of mitosis.

What goes on during cytokinesis in mitosis

During cytokinesis in mitosis, the cytoplasm divides between the two daughter cells, forming a cleavage furrow in animal cells or a cell plate in plant cells, leading to the complete separation and formation of two distinct cells.

what type of cell division is this

mitosis

what type of meiosis is this

meiosis 1

what type of meiosis is this

meiosis 2