HESI A2 Biology Cells

nucleus

contains genetic material (DNA) stored in chromosomes

endoplasmic reticulum

network of membranes that transports material within the cell

consists of rough and smooth ER

rough ER

protein and cell membrane synthesis, covered in ribosomes

smooth ER

metabolism and detoxification, no ribosomes

ribosomes

protein factories of the cell

Golgi apparatus

modifies, packages, transports proteins/lipids to destination

Lysosomes

digests/recycles waste

vacuoles

Stores food, water, wastes, and other materials and helps maintain internal pressure

mitochondria

powerhouse of the cell

Cytoskeleton

exclusive to eukaryotic cells

A network of fibers that holds the cell together, helps the cell to keep its shape

consists of microfilaments, intermediate filaments and microtubules

animal cell

has a defined nucleus, small vacuole, membrane-bound organelles, has cytoskeleton but no cell wall

plant cell

defined nucleus, large vacuole, chloroplasts, cell wall made of cellulose and membrane-bound organelles

prokaryotic cells

cells without a nucleus (has a nucleoid region) or other membrane-bound organelles

where does active transport occur?

within the cell membrane

mitosis prophase

- Chromatin condenses into visible chromosomes (X-shaped)

- Spindle fibers begin to form

- Centrosomes move to opposite poles

mitosis prometaphase

Nuclear envelope breaks down completely

- Spindle fibers attach to chromosomes at their kinetochores (a protein on the centromere)

- Chromosomes begin moving toward the center

mitosis metaphase

- Chromosomes align in the middle of the cell (metaphase plate)

- Spindle fibers are fully connected to kinetochores

mitosis anaphase

- Sister chromatids separate and are pulled toward opposite poles

- Spindle fibers shorten

mitosis telophase

- Two nuclear envelopes reform around separated chromosomes

- Chromosomes begin to uncoil back into chromatin

- Spindle breaks down

mitosis

part of eukaryotic cell division during which the cell nucleus divides into two identical diploid daughter cells

Cytokinesis

division of the cytoplasm to form two separate daughter cells

when does cytokinesis occur in mitosis

once after telophase

when does cytokinesis occur in meiosis

telophase 1 and telophase 2

meiosis

Meiosis is the process that produces 4 genetically unique haploid gametes (sperm or egg cells) from one diploid parent cell.

meiosis prophase 1

DNA condenses, matching chromosomes pair up, crossing over occurs, spindle fibers start forming

meiosis prometaphase 1

Nuclear envelope breaks down (the nucleus disappears).

Spindle fibers attach to the chromosomes.

meiosis metaphase 1

Pairs of chromosomes line up across the middle of the cell.

meiosis anaphase 1

The pairs are pulled apart to opposite sides of the cell.

Each side gets one chromosome from each pair.

meiosis telophase and cytokinesis 1

The cell splits into two.

Each new cell has half the number of chromosomes of the parent cell

meiosis prophase 2

Chromosomes get ready again in each of the two new cells.

Spindle fibers start forming.

meiosis prometaphase 2

Nuclear envelope breaks down (again).

Spindle fibers attach to chromosomes.

meiosis metaphase 2

Chromosomes line up in the middle of each cell.

meiosis anaphase 2

The two halves of each chromosome (sister chromatids) are pulled apart.

meiosis telophase and cytokinesis 2

Both cells split again → you end up with 4 new cells.

Each has half the DNA (haploid) and is genetically different.

diploid

(2n) two sets of chromosomes from each parent

46 chromosomes

haploid

(n) having a single set of unpaired chromosomes

23 chromosomes

binary fission

A form of asexual reproduction in prokaryotes (like bacteria) where one cell divides into two identical cells.

no nucleus involved

what type of cellular reproduction is mitosis

asexual, occurs in body cells

what type of cellular reproduction is meiosis

sexual, occurs in sex cells (gametes)

when do chromosomes line up in the middle of the cell?

metaphase