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How do bacteria divide?

Binary fusion

What is prokaryotic cell division?

Binary fission- One cell splits into (2) identical daughter cells.

Steps of Binary Fusion

1. DNA replicates

2. Cell elongates

3. Septum forms (membrane pinches in)

4. Cells splits

Result of prokaryotic cell division

(2) genetically identical daughter cells

Process of Mitosis?

1. Prophase- Chromosomes condense, spindle forms

2. Metaphase- Chromosomes line up in the middle

3. Anaphase- Sister chromatids separate

4. Telophase- (2) nuclei form

5. Cytokinesis- Cell splits

Results of Mitosis?

(2) genetically identical daughter cells with the same number of chromosomes as the parent cell.

Mitosis?

Process where the cell’s nucleus divides & separates the duplicated chromosomes into (2) identical sets. Before it starts the cell has already copied it’s DNA during the S phase of the cell cycle.

What is a chromosome?

A structure made of DNA & proteins that carries genetic info (genes) in the nucleus.

Chromosome?

A structure made of DNA & proteins that carries genetic Information (genes) in the nucleus.

Duplicated Chromosomes?

A chromosome that has been copied during DNA replication, consisting of (2) identical sister chromatic.

Sister Chromatids?

(2) identical copies of a chromosome that are attached together before cell division.

Centromere?

The region that holds sister chromatids together & where spindle fibers attach during mitosis.

What is the cell cycle?

The series of stages a cell goes through to grow, copy DNA, & divide into (2) daughter cells.

What are the (2) main parts of the cell cycle?

Interphase and M phase (mitotic phase)

What happens during interphase?

The cell grows, copies DNA, & prepares for division.

Stages:

G1-S-G2

What happens during the S phase?

DNA replication occurs & chromosomes are duplicated.

What happens during M phase?

The cell divides through mitosis & cytokinesis, producing (2) identical daughter cells.

Grow-Copy DNA-Prepare-Divide

What are cell cycle checkpoints?

Control points where the cell checks if conditions are correct before continuing the cell cycle.

What is checked at the G2 checkpoint?

Whether DNA was replicated correctly.

What is checked at the G1 checkpoint?

Cell size, nutrients, & DNA damage before DNA replication.

What is checked at the M checkpoint?

If chromosomes are properly attached to spindle fibers before separation.

How are checkpoints related to cancer?

When checkpoint control fails, cells divide uncontrollably, leading to cancer.

What are proto-oncogenes?

Normal genes that promote cell growth and division.

What is an oncogene?

A mutated proto-oncogene that cause uncontrolled cell division.

Why do tumor suppressor genes do?

They slow or stop cell division, repair DNA, or trigger cell death.

What happens when tumor suppressor genes mutate?

Cells divide uncontrollably, which can lead to cancer.

What is meiosis?

Cell division that produces haploid sex cells (gametes).

What is the purpose of meiosis?

To reduce the chromosome number in half & produce genetically unique gametes.

How many cells are produced in meiosis?

(4) haploid daughter cells.

Why are cells produced by meiosis genetically different?

Because of crossing over & independent assortment,

What is crossing over?

Exchange of DNA between homologous chromosomes during Prophase I of meiosis.

What is the independent assortment?

Random separation of homologous chromosome pairs during Metaphase I of meiosis.

What are crossing over and independent assortment important?

They create genetic variation in gametes.

What is a diploid cell?

A cell with (2) sets of chromosomes (2n)

What is a haploid cell?

A cell with one set of chromosomes (n)

What types of cells are diploids?

Body cells (somatic cells)

What types of cells are haploids?

Gamates (sperm & egg cells)

For how many chromosomes do human diploid cells have?

46 chromosomes (23 pairs).

How many chromosomes do human haploid cells have?

23 Chromosomes

What are homologous chromosomes?

Pairs of chromosomes with the same genes, (1) from each parent.

What are sister chromatids?

Identical copies of a chromosome connected by a centromere.

When do homologous chromosomes pair?

During meiosis I

When do sister chromatids separate?

During mitosis & meiosis II

What is fertilization?

The fusion of sperm and egg cell to form a diploid zygote.

How many chromosomes does a human zygote have?

46 chromosomes (23 pairs)

Why does fertilization increase genetic variation?

Because of random fertilization & mixing of genes from (2) parents.

What is a zygote?

The 1st diploid cell formed after fertilization

What is a genotype?

The genetic makeup of an organism (the alleles it has).

Example: AA

What is a phenotype?

The observable physical trait of an organism

Example: blue eyes

What is a dominant allele?

An allele that is expressed when only one copy is present.

Bb

What is a recessive allele?

An allele that is only expressed when (2) copies are present

bb

Homozygous?

Having (2) identical alleles for a gene.

Heterozygous?

Having (2) different alleles for a gene

Bb

What is a homozygous dominant?

(2) dominant alleles

AA

What is a homozygous recessive?

Two recessive alleles (aa)

Why is a Punnett square?

A diagram used to predict possible genetic combinations of offspring.

What does a Punnett square show?

Possible genotypes, phenotypes, and probabilities of offspring traits.

What is the genotype ration of Aa x Aa?

3 dominant: 1 recessive

What happens in the G1 phase?

Cell grows, makes proteins and organelles, and prepares for DNA replication.

What happens in G0 phase?

A phase where cells leave the cell cycle and stop dividing, but still perform normal functions. Ex: Nerve & Muscle cells

What happens during the S phase?

DNA replication occurs and chromosomes are duplicated.

What forms after DNA replication?

A duplicated chromosome with (2) sister chromatids.

What happens during G2 phase?

Cell prepares for mitosis, grows, produces proteins, & checks for DNA replication.

What is interphase?

The longest part of the cell cycle, where the cell prepares for division it includes: G1, S, G2. This is the stage where cell grows, replicates DNA, & prepares for division.

What phase replicates DNA before cell division?

S phase

What is a miototic appearance of the cell?

Means that the cell is actively dividing. Chromosomes are condensed and visible during cell division.

Stages of Mitosis in order?

Prohase

Metaphase

Anaphase

Telophase

What happens during prophase?

Chromosomes condense,

Nucleus membrane breaks down,

Spindle fibers form.

Metaphase?

Chromosomes line up in the center of the cell.

What happens during anaphase?

Sister chromatids separate and move to opposite poles.

What happens in telophase?

(2) new nuclei form and chromosomes uncoil.

What is cytokinesis?

Division of the cytoplasm to form (2) cells.

Two types of cytokinesis?

Cleavage furrow (animals)

Cell plate (plants)

What is Cancer?

Uncontrolled cell division caused not mutations in cell cycle genes.

What causes Cancer?

DNA mutate ions from radiation, chemicals, viruses, or inherited genes.

Characteristics of cancer cells?

Uncontrolled division, ignore checkpoints, form tumors, avoid cell death.

What is metastasis?

The spread of cancer cells to other parts of the body.

How do haploid and diploid relate to sexual life cycle?

Diploid cells undergo meiosis to produce haploid gametes; fertilization restores the diploid zygote.

(2) critical features of a sexual life cycle?

Meiosis and syngamy (fertilization)

What is meiosis?

Cell division that produces (4) haploid gametes.

Purpose of meiosis?

Reduces chromosomes number and creates genetic variation

What does meiosis produce?

(4) haploids

What separates in Meiosis I?

Homologous chromosomes

What separates in meiosis II?

Sister chromatids

Stages of meiosis in order?

Meiosis I:

Prophase I

Metaphase I

Anaphase I

Telophase I

Meiosis II:

prophase II

Metaphase II

Anaphase II

Telophase II

What happens in Phrophase I?

Homologous chromosomes pair, crossing over occurs, chromosomes condense.

What is crossing over?

Exchange of DNA between homologous chromosomes during Prophase I of meiosis.

What happens in Metaphase I?

Homologous chromosomes pairs line up in the center of the cell.

What separates in Anaphase I?

Homologous chromosomes

What is produced after Telophase I?

(2) haploid cells

What happens in in Prophase II?

Chromosomes condense and spindle fibers form.

What happens in Metaphase II?

Chromosomes line up in the center of the cell

What separates in Anaphase II?

Sister chromatids

Describe Telophase II?

Nuclear membranes form

Cytokinesis occurs

Result= (4) haploid daughter cells, each one unique

What is gametogenesis?

Formation of gamates through meiosis.

Where does gametogenesis occur?

Testes, spermatogenesis

Ovaries, oogenesis

where does gametogenesis occur?

Testes (sperm) and ovaries (eggs)

Steps of spermatogenesis?

Spermatogonium,

Primary spermatocyte,

Secondary spermatocyte,

Spermatids,

Sperm

Steps of Oogenesis?

1. Oogonium

2. Primary Oocyte

3. Secondary Oocyte

4. Polar bodies

5. Ovum (egg)

Why is oogenesis atypical?

Produces (1) egg and polar bodies due to unequal division.