Cell division/ differeciation

What is the main purpose of cell division in organisms?

Cell division occurs for growth, maintenance, repair, and reproduction.

What are the two main reasons cells divide rather than continue to grow?

1) Larger cells place more demands on their DNA. 2) Larger cells have difficulty moving nutrients and wastes across the cell membrane.

What is cell differentiation?

Cell differentiation is the process by which cells become specialized to perform different functions.

What are three specialized cell types in animals?

Red blood cells, muscle cells, and skin cells.

What is the process called when a single cell divides into two daughter cells?

Cell division.

What must happen before a cell divides?

The cell must make a copy of its entire DNA.

What are chromosomes?

Chromosomes are thread-like structures in the nucleus made of DNA tightly coiled around proteins called histones.

How many chromosomes do humans have?

Humans have 46 chromosomes.

What are the main stages of the cell cycle?

The cell cycle consists of Interphase and M Phase.

What phases make up Interphase?

G1 (gap phase), S (DNA synthesis), and G2 (preparation for division).

What occurs during the S phase of Interphase?

DNA replication occurs in preparation for division.

What is M Phase?

M Phase consists of Mitosis (division of the nucleus) and Cytokinesis (division of the cytoplasm).

What are the four stages of Mitosis?

Prophase, Metaphase, Anaphase, and Telophase.

What happens during Prophase?

The nuclear membrane breaks down and chromosomes become condensed.

What occurs during Metaphase?

Chromosomes line up across the center of the cell and are connected to spindle fibers.

What happens during Anaphase?

Chromosomes separate and are moved to opposite ends of the cell.

What occurs during Telophase?

Chromosomes gather at opposite ends and lose their distinct shapes; two new nuclear membranes form.

What is Cytokinesis?

Cytokinesis is the division of the cytoplasm to yield two daughter cells.

What are sister chromatids?

Sister chromatids are identical copies of a chromosome connected by a centromere.

What is the role of spindle fibers?

Spindle fibers are responsible for moving chromosomes to opposite poles during mitosis.

What are centrioles?

Centrioles are barrel-shaped organelles involved in organizing the mitotic spindle and completing cytokinesis, found only in animal cells.

What are cyclins?

Cyclins are proteins that regulate the timing of the cell cycle.

What is uncontrolled cell growth also known as?

Cancer.

What are the two types of tumors?

Benign tumors (non-cancerous) and malignant tumors (cancerous).

What is metastasis?

Metastasis is when pieces of a malignant tumor break off and infect other parts of the body.

What is a carcinogen?

A carcinogen is a chemical known to cause cancer.

What is a gene?

A gene is a stretch of DNA that codes for a specific protein, determining traits.

What are alleles?

Alleles are different or alternative forms of a gene.

Who is Gregor Mendel?

Gregor Mendel was an Austrian monk who conducted the first research on genetics using pea plants.

What was Mendel's observation with the F1 Generation of pea plants?

Mendel observed that the offspring (F1 Generation) were all tall when he crossed a tall pea plant with a short pea plant.

What was the result of crossing a tall pea plant with a short pea plant in Mendel's experiment?

All offspring (F1 Generation) were tall.

What does the principle of dominance state?

Some alleles are dominant and others are recessive.

What are the physical characteristics of an organism called?

Phenotype.

What is the genetic composition of an individual known as?

Genotype.

What are homozygous alleles?

Alleles that are identical for a particular trait (e.g., TT or tt).

What are heterozygous alleles?

Alleles that are different for the same trait (e.g., Tt).

What is the process called when alleles are separated during gamete formation?

Segregation.

What is a Punnett square used for?

To predict the possible genotypes of offspring from parental genotypes.

What is a Monohybrid Cross?

A genetic cross that involves one trait.

What is a Dihybrid Cross?

A genetic cross that involves two different traits.

What is incomplete dominance?

A situation where alleles mix and do not show true dominance.

What is codominance?

A situation where both alleles are expressed equally in the phenotype.

What is an example of codominance in cattle?

Red and white haired cattle producing offspring with roan coat color.

What are multiple alleles?

A situation where there are three or more alleles for a gene.

What determines sex in most eukaryotic organisms?

Sex chromosomes.

What are the sex chromosomes in humans?

X and Y chromosomes.

What is a pedigree?

A diagram of family relationships used to visualize genetic relationships.

What do squares and circles represent in a pedigree?

Squares represent males and circles represent females.

What is the difference between dominant and recessive traits?

Dominant traits require only one affected parent, while recessive traits require both parents to be carriers.

What is meiosis?

The process of cell division that reduces the number of chromosomes in gametes to half.

What is the difference between diploid and haploid cells?

Diploid cells contain two sets of chromosomes; haploid cells contain one set.

What is crossing over?

The exchange of chromosome segments between homologous chromosomes during meiosis.

What is karyotyping?

A test to examine chromosomes in a sample of cells to identify genetic problems.

What does a normal human karyotype consist of?

22 pairs of autosomal chromosomes and one pair of sex chromosomes (46,XX for females and 46,XY for males).

What can variations from the standard karyotype lead to?

Developmental abnormalities.

How are chromosomes matched to create a karyotype?

By size, banding pattern, and centromere position.