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Biology > Cell Division > Flashcards

Cell Division Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Prokaryotic and Eukaryotic Cells Division

A

Prokaryotic divides through binary fission
Eukaryotic divides through mitosis

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2
Q

Importance of Centromere

A

Essential for the proper segregation of chromosomes during cell division

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3
Q

Condensation of Chromosomes

A

Nucleosomes wrap in a helical fashion to form a thick supercoil that stack over each other forming a single thick fiber named chromatin

Chromatin coils even further to form chromosomes which carries genetic information in the form of genes

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4
Q

How do Chromosomes Move

A

Kinetochores and Microtubules

Kinetochores are protein complexes that form on the centromere during cell division, and provide an attachment point for spindle fibers with the centromere region

Microtubules are hollow cylinders that can rapidly assemble and disassemble at the centrosome

Microtubules and Kinetochores work together by lengthening and shortening the microtubules to move chromosomes during cell division

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5
Q

The 4 Phases of Mitosis

A

Prophase

Metaphase

Anaphase

Telophase

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6
Q

Prophase Events

A

Chromatin condense into chromosomes by supercoiling and becoming visible

The nuclear membrane starts disappearing

Centrosomes move to opposite poles of the cell and the microtubules start to form

Kinetochores start to appear on centromeres

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7
Q

Metaphase Events

A

Nuclear membrane disappears completely

Microtubules grow and attach to centromere’s kinetochores, and move them to align both sister chromatids towards the equator of the cell

Each sister chromatid faces a pole, and the spindle fibers are fully developed

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8
Q

Anaphase Events

A

Kinetochores use spindle fibers to split the centromere of each sister chromatid, thus pulling them to opposite poles

Each sister chromatid becomes a chromosome

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9
Q

Telophase Events

A

Microtubule spindle fibers disintegrate

The nuclear membrane reforms around the daughter chromosomes

Chromosomes uncondensed and coil back to become no longer visible

During the entire process of mitosis, the cell undergoes cytokinesis and ends in telophase

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10
Q

Oogenesis Unequal Cytokinesis

A

Oogonia grows into primary oocyte

Primary oocyte undergoes Meiosis I which results in unequal cytokinesis

A large secondary oocyte forms which contains most of the cytoplasm which will become the mature egg, but the other daughter cell (polar body) has very little cytoplasm and eventually degenerates

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11
Q

Budding Unequal Cytokinesis

A

A small bud sticks out from the parent yeast cell

The cytoplasm and organelles are unequally distributed, with the bud receiving a smaller portion compared to the parent cell

Over time, the bud grows and separates from the parent cell and becomes a new independent yeast cell

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12
Q

Cytokinesis in Animal Cell

A

A contractile protein ring forms around the equator of the cell and pulls the plasma membrane inwards. This inward pull is called the cleavage furrow, and when the cleavage furrow reaches the center of the cell it is pinched apart to form two daughter cells

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13
Q

Cytokinesis in Plant Cell

A

Vesicles that come from the Golgi move to the center of the cell, and fuse together to form a cell plate. The cell plate continues to develop until it joins with the cell’s plasma membrane which completes the division of the cytoplasm, then both daughters secrete cellulose to form their new cell walls.

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14
Q

Haploid and Diploid

A

Haploid: Contains one set of chromosomes and formed by meiosis

Diploid: Contains two sets of chromosomes and formed by mitosis

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15
Q

Homologous Chromosomes

A

Pairs of non-identical chromosomes in a diploid cell that are inherited from parents. They have same length, gene sequence, centromere positions, and same gene locus. They only differ from each other by alleles

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16
Q

Meiosis

A

Reduction division in which the chromosome number is halved from diploid o haploid, resulting in genetically different cells

17
Q

Prophase I Events

A

Replicated chromosomes condense by supercoiling and becoming visible

Replicated homologous chromosomes pair up to form bivalent and undergo crossing over

Spindle fibers form and stretch out from each pole to the equator

The nuclear membrane starts to break down

18
Q

Metaphase I Events

A

The nuclear membrane is fully broken down

The paired up homologous chromosomes line up at the equator randomly and independently of each other

The spindle microtubules attach to the centromeres of the homologous chromosomes

19
Q

Anaphase I Events

A

Homologous chromosomes pairs are pulled to opposite poles thus halving the chromosome number

Centromeres do not split

20
Q

Telophase I Events

A

Spindle microtubules disintegrate, and each chromosome from the homologous pair is found at opposite poles

A nuclear membrane starts reforming around each daughter nucleus

The membrane divides through Cytokinesis I

Chromosomes uncondensed and uncoil

21
Q

Meiosis I VS Meiosis II

A

Synapsis and crossing over occurs in Prophase I
Synapsis and crossing over doesn’t occur in Prophase II

Homologous pairs of chromosomes line up in the equator
Sister chromatids line up in the equator

Homologous pairs of chromosomes separate and move to opposite poles of the cell
Sister chromatids separate and move to opposite poles of the cell

2 haploid cells are formed
4 haploid cells are formed

22
Q

Mitosis VS Meiosis

A

Takes place in body cells
Takes place in germ cells

Produces body cells
Produces gametes

Has 1 division
Has 2 divisions

2 identical diploid daughter cells are formed
4 different haploid daughter cells are formed

No crossing over
Crossing over

No variation
Variation

23
Q

Crossing Over and Process

A

Exchange of alleles between non-sister chromatids of homologous chromosomes

In Prophase I, homologous chromosomes undergo synapsis thus forming a bivalent

A cut called SSB (Single Stranded Break) is made at the same part of DNA of each of the non-sister chromatids

Each non-sister chromatid re-joins with its homologous partner where they can then exchange genetic material through the chiasmata.

The chromatids formed after crossing over are called recombinant chromatids

24
Q

Independent Assortment

A

In Metaphase I, bivalents line up randomly and independently of each other on the equator

Since they line up in any orientation on the equator, they segregate randomly

The possible combination of gametes depends on the number of homologous pairs and is calculated using 2^n,where n is the haploid number of chromosomes

25
Q

Down Syndrome and Non-disjunction

A

Non-disjunction is when chromosomes fail to separate during gamete formation

Can happen in Anaphase I or II

In Anaphase I, the chromosomes pair fail to separate properly which results in the formation of 4 abnormal cells

In Anaphase II, the sister chromatids fail to separate properly which results in the formation of 2 abnormal cells

26
Q

Interphase Processes

A

DNA Replication

Organelle Duplication

Cell Growth

Transcription and Translation

Protein Synthesis

27
Q

Interphase Stages

A

G1: Where the cell grows and duplicates organelles and synthesizes proteins

S: Where DNA is replicated

G2: Where the cell continues to grow and make proteins needed for metabolic reactions in mitosis

28
Q

Cell Growth during Interphase

A

DNA Replication: DNA is doubled through replication

Cytoplasmic Growth: Volume of the cytoplasm increases

Organelle Duplication: Mitochondria and chloroplast divide, mb-bound bud off from existing ones, and non-mb bound are assembled from the beginning

Protein Synthesis Cell synthesizes more proteins for more cellular processes

29
Q

Cyclins

A

Proteins that control the progression of cells through the cycle, and act as checkpoints between two stages to ensure every task is performed

Cyclins bind to enzymes named CDK’s (cyclin dependent kinases) which phosphorylate specific proteins therefore making them become active and carry out tasks to continue the cell cycle. After the event occurred, the cyclin is degraded and the CDK is inactive

30
Q

Purpose of Control of Cell Division

A

Ensures that each daughter cell receives an exact copy of their parent’s DNA

Maintains proper cell numbers by preventing uncontrolled division

Allows for cell differentiation to create various cell types

Allows for organism growth, tissue repair, and wound healing

31
Q

Benign VS Malignant

A

Slow pace
Rapid and uncontrolled pace

Do not spread from site of origin
Detach and spread throughout the body

Unlikely to cause harm
Can cause harm and made of the same type of cell as the primary tumor

Not life-threatening
Life-threatening, known as cancer

32
Q

Characteristics of Cancer Cells

A

Do not differentiate

Have abnormal nuclei

Form tumor

Undergo metastasis

33
Q

Mitotic Index

A

A measure of how fast cells are dividing

Formula is:

Cells in mitosis / total number of cells

34
Q

Cell Proliferation

A

A rapid increases in the number of cells, and happens when cell division happens at a faster rate than cell death

Used in multicellular organisms for growth, cell replacement and tissue repair

35
Q

Cell Proliferation in Growth

A

In animals, the zygote divides rapidly by mitosis and becomes and embryo. This continues until the animal reaches an adult size where growth and cell proliferation stops

In plants, meristems, unspecialized cells found at the tip of a shoot and a root, are where cell proliferation occurs.

36
Q

Cell Proliferation in Cell Replacement

A

When cells are lost from the epidermis of the skin, more cells are produced to replace them

Cell division happens in the basal later of the epidermis. The cells then get moved towards the skin surface by continued cell division. The continuous cell division allows for the production of a tough protein called keratin, which is hydrophobic and causes cells to dry out, and by the time the cells reach the skin surface they’re flattened and dead.

37
Q

Cell proliferation in Tissue Repair

A

Wounds to many prats of the body can heal by using cell division to replace lost cells. This depends on the presence of undifferentiated stem cells that can divide and then differentiate.

If there are basal cells present in the skin, they can regenerate outer layers of skin in a few days

If the damage in the skin is so severe that there’s no stem cells, then skin grafts may be needed

Biology (24 decks)

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