Biology Chapters 11 & 12

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HOW CELLS REPRODUCE - One of the characteristics of living things is their ability to

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REPRODUCE

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HOW CELLS REPRODUCE - HEREDITY is

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the transfer of biological information from parent to offspring.

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HOW CELLS REPRODUCE - GENES are

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the units of heredity.

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HOW CELLS REPRODUCE - Genes are located

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on CHROMOSOMES

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HOW CELLS REPRODUCE - Chromosomes are made up of

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DNA twisted together and tightly packed around proteins.

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HOW CELLS REPRODUCE - Each species is unique due to the number of

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chromosomes and arrangement of genes on the chromosome.

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CHROMOSOMES - All sexually reproducing organisms have

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PAIRS of chromosomes.

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CHROMOSOMES - DNA and proteins are in the form of

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CHROMATIN In the nucleus of non-dividing cells

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CHROMOSOMES - the thin strands of chromatin twist into thick strands called

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CHROMATIDS during cell division

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CHROMOSOMES – A CHROMOSOME forms when

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two chromatids are held together by a CENTROMERE

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CHROMOSOMES - HOMOLOGOUS chromosomes are

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pairs of chromosomes that are similar in size, shape, and genetic content.

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CHROMOSOMES – Do Homologous chromosomes have the same DNA sequences?

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No, at a particular location the two chromosomes may have different DNA sequences. This means that they can produce different FORMS of a trait in an organism.

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CHROMOSOMES - The 46 human chromosomes in human somatic (BODY) cells are

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2 sets of chromosomes—1 set from MOM and 1 set from DAD

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CHROMOSOMES - Diploid cells contain

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BOTH sets of chromosomes.

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CHROMOSOMES – Diploid cells are written as

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2n

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CHROMOSOMES - Human somatic cells are

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diploid (46 chromosomes or 23 PAIRS)

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CHROMOSOMES - Haploid cells contain

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ONE set of chromosomes

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CHROMOSOMES – Haploid cell are written as

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n or 1n

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CHROMOSOMES – Haploid Human gametes (eggs and sperm ) contain

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23 chromosomes

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CHROMOSOMES - 22 pairs of chromosomes in human somatic cells are called

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AUTOSOMES

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CHROMOSOMES - Autosomes determine

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most hereditary information about the child except for the GENDER.

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CHROMOSOMES - The last pair of chromosomes is called

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SEX chromosomes

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CHROMOSOMES – What determines the gender of the child

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sex chromosomes are used to determine the gender of the child.

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CHROMOSOMES – What are the human sex chromosomes

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the two sex chromosomes are X and Y

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CHROMOSOMES – female chromosomes are

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XX chromosomes - female

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CHROMOSOMES – male chromosomes are

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XY chromosomes – male

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CHROMOSOMES – Which parent determines the sex of an offspring?

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Because a female can only donate an X chromosome, the sex of an offspring is determined by the MALE

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CHROMOSOMES - Most living cells are between 2-20 μm in diameter. Once cells reach a certain size, they must stop growing or

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DIVIDE

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CHROMOSOMES - Some cells do not normally divide:

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1. Nerve cells 2. Cardiac muscle cells 3. Mature red blood cells (RBCs)

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CELL DIVISION – Why do cells divide?

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Because a cell can only grow so big, cell division is important for cell survival.

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CELL DIVISION - Eukaryotic organisms divide by:

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Mitosis and Meosis

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CELL DIVISION – What is MITOSIS

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division of body cells in which identical cells are reproduced.

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CELL DIVISION – What are the cells produced in Mitosis used for

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Used for TISSUE REPAIR and replacement of worn out cell parts b. GROWTH of an organism. c. Production of OFFSPRING in some organisms.

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CELL DIVISION – What is MEOISIS

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division of SEX cells.

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CELL DIVISION - Prokaryotic organisms divide by

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BINARY FISSION

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CELL DIVISION - Binary Fission is

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A form of asexual reproduction that produces IDENTICAL offspring.

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CELL DIVISION – Clones are produced by

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asexual reproduction, a single parent passes exact copies of all its DNA to its offspring (CLONES).

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The CELL CYCLE is

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the continuous cycle of cellular growth and reproduction.

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CELL CYCLE - Stages of the cell cycle:

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1. Interphase 2. Mitosis 3. Cytokinesis

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CELL CYCLE – Stages of Interphase

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i. G1 ii. S iii. G2

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CELL CYCLE - Interphase is the _____ stage of the cycle

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Interphase is the LONGEST part of the cell cycle

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CELL CYCLE – What happens in Interphase stage 1 G1

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(Gap or Growth Phase One) Phase—growth in SIZE and ORGANELLE number. Cellular activities take place during this phase.

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CELL CYCLE – What happens in Interphase stage 2 S Phase

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Chromosomes are formed and DUPLICATED

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CELL CYCLE – Interphase stage 3 G2

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(Gap or Growth Phase Two) Phase—cell makes proteins for mitosis and centrioles are duplicated.

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CELL CYCLE – Stages of Mitosis

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i. PROPHASE ii. METAPHASE iii. ANAPHASE iv. TELEPHASE

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CELL CYCLE – Structures involved in MITOSIS

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i. Spindle Apparatus ii. Centrioles iii. Kinetichores

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CELL CYCLE - MITOSIS The Spindle apparatus Consists of

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microtubules which are organized into sets of two called SPINDLE FIBERS

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CELL CYCLE - MITOSIS What is the Function of spindle fibers:

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REMOVING chromosomes during mitosis

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CELL CYCLE - MITOSIS The Centrioles are found in

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Found in ANIMAL cells only (plants have centrosomes)

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CELL CYCLE - MITOSIS Centrioles are found

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outside the nucleus

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CELL CYCLE - MITOSIS Centrioles shape

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A pair of barrel-shaped structures

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CELL CYCLE - MITOSIS Centrioles Function is

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assembling and disassembling SPINDLE FIBERS.

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CELL CYCLE - MITOSIS Kinetichores shape

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Small, disk-shaped structure.

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CELL CYCLE - MITOSIS Kinetichores serve as

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the POINT OF ATTACHMENT between chromatids and spindle fibers and attach to each side of the centromere.

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CELL CYCLE - MITOSIS The Phases of mitosis include

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prophase, metaphase, anaphase, and telophase

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CELL CYCLE – Mitosis stage 1

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Prophase

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CELL CYCLE – MITOSIS STAGE 1 What happens in Prophase

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i. Chromosomes shorten and thicken (CONDENSE) making them visible in a light microscope. ii. Nuclear envelope and nucleoli BREAKDOWN iii. Microtubles start moving centrioles to the POLES of the cell. iv. Spindle fibers from each poles extend toward the chromosomes and attach to KINETIC CORES on either side of the centromere and start pulling on the chromosome to opposite poles.

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CELL CYCLE – MITOSIS STAGE 1 Draw cell in prophase:

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DRAWING - chromosomes look like fuzzy spaghetti -begin crossing (centromeres forming) - breakdown nuclear envelope - start spindle fibers -centrioles begin to move towards poles

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CELL CYCLE – MITOSIS STAGE 2

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Metaphase

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CELL CYCLE – MITOSIS STAGE 2 What happens in Metaphase

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Chromosomes become aligned MIDWAY between the poles of spindle fibers in a random manner. Chromosomes are very distinct and are used for genetic studies at this stage.

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CELL CYCLE – MITOSIS STAGE 2 Draw a cell in metaphase:

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DRAWING - chromosomes start to align in the middle - spindle fibers are evident - centrioles are at the poles

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CELL CYCLE – MITOSIS STAGE 3

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Anaphase

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CELL CYCLE – MITOSIS STAGE 3 What happens in Anaphase

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i. Sister chromatids of each chromosome are PULLED APART at the centromere by the spindle fibers.

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CELL CYCLE – MITOSIS STAGE 3 Draw a cell in anaphase

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DRAWING - chromatids pull towards the poles, centromeres divide,

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CELL CYCLE – MITOSIS STAGE 4

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Telophase

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CELL CYCLE – MITOSIS STAGE 4 What happens in telophase

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i. Chromosomes return to a threadlike (CHROMATIN) form. ii. Nuclear envelope and nucleoli REAPPEAR iii. Spindle apparatus BREAKSDOWN iv. The two daughter nuclei have the same NUMBER of chromosomes as the mother cell.

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CELL CYCLE – MITOSIS STAGE 4 Draw a cell in telophase

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DRAWING - two sister cells developed, spaghetti back in place, nuclear envelope in place, no spindles

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CELL CYCLE – Final Phase

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Cytokinesis

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CELL CYCLE – Cytokineses is

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the division of CYTOPLASM

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CELL CYCLE – Why does Cytokineses occur?

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Mitosis divides the NUCLEUS - not the cytoplasm, so cytokinesis must take place to complete the formation of two daughter cells.

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CELL CYCLE – Cytokineses usually occurs

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between late anaphase and the end of telophase.

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CELL CYCLE – Cytokineses PLANT CELL Does Cytokineses occur in Plant cells

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No - Because of the rigid CELL WALL, plant cells can’t be pinched into.

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CELL CYCLE – Cytokineses PLANT CELL What replaces Cytokineses (cytoplasm split) in a plant cell

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i. Microtubules found on the inside of the cell membrane guide vesicles from golgi bodies to the division plane. iii. The vesicles contain wall building contents that fuse together to form a CELL PLATE iv. The plate expands until it reaches the CELL/PLASMA MEMBRANE where it attaches and separates the cytoplasm.

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CELL CYCLE - Cytokineses PLANT CELL In time the cell plate develops in the

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_________________.

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CELL CYCLE - Cytokineses ANIMAL CELL What is a CONTRACTILE RING

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a band of actin and myosin filaments that wraps around the cell’s midsection

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CELL CYCLE - Cytokineses ANIMAL CELL Where is the CONTRACTILE RING located

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Under the plasma membrane is called a CONTRACTILE RING

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CELL CYCLE - Cytokineses ANIMAL CELL The contractile ring contracts

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INWARD pulling the attached plasma membrane with it.

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CELL CYCLE - Cytokineses ANIMAL CELL The indentation that forms is called

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a CLEAVAGE FURROW

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CANCER – How does cancer begin

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Checkpoints in the cell cycle allow problems to be correct before the cycle advances. Sometimes these fail and a cell makes too little or too much of its product.

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CANCER - When all checkpoint mechanisms fai

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a cell loses control over its cell cycle and may form a TUMOR in surrounding tissues.

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CANCER – What is usually missing in tumor cells

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Usually one or more checkpoint gene products are missing in tumor cells.

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CANCER - Tumor suppressor gene products

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INHIBIT mitosis

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CANCER - ONCOGENES are

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any genes that help transform a normal cell into a tumor cell.

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CANCER - Proto-oncogene are

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genes that encode proteins that STIMULATE mitosis. CANCER - Mutations can turn Proto-oncogenes into ONCOGENES

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CANCER – What is NEOPLASM

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abnormal masses of cells that lack control over how they grow and divide.

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CANCER - BENIGN neoplasms

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stay in one place and are not cancerous.

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CANCER - MALIGNANT neoplasms are

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cancerous.

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CANCER - AKA malignant

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neoplasms

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CANCER – Malignant neoplasm Cells grow and divide

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ABNORMALLY

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CANCER – Malignant neoplasm abnormal cells lose

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Controls on growth and division

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CANCER – Malignant neoplasm abnormal cells increase

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Capillary blood supply to the cells.

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CANCER – Metastasis cells have

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altered recognition proteins and weakened adhesion allowing them to break away and invade distant tissues (METASTASIS)

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MEOSIS - ASEXUAL REPRODUCTION – means

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One parent produces offspring.

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MEOSIS - ASEXUAL REPRODUCTION - All offspring are genetically

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identical to one another and to parent.

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MEOSIS - ASEXUAL REPRODUCTION - Many offspring can be produced in

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a short time.

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MEOSIS - ASEXUAL REPRODUCTION - Types of asexual reproduction

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Binary Fission, Budding, Fragmentation, Vegetative Propagation

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MEOSIS - SEXUAL REPRODUCTION is

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Production of offspring from 2 different gametes that combine during fertilization.

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MEOSIS - SEXUAL REPRODUCTION Why is genetic variation important among offspring

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it is important for the process of adaptation and evolution

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MEOSIS - SEXUAL REPRODUCTION Takes a longer amount of

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time than asexual reproduction. which is considered a con

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MEOSIS - SEXUAL REPRODUCTION Gametes are produced through

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meiosis

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MEIOSIS VOCABULARY – Gametes

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sex cells (sperm and eggs)

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MEIOSIS VOCABULARY – Diploid -

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contain two sets of chromosomes, written as 2n (somatic cells)

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MEIOSIS VOCABULARY – Haploid -

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contain one set of chromosomes, written as n or 1n (sex cells)

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MEIOSIS VOCABULARY – Homologous chromosomes

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- pairs of chromosomes that are the same size, shape, and code for the same traits.

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MEIOSIS VOCABULARY – Somatic Cells

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- any body cell other than a sperm or egg cell.

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MEIOSIS - During meiosis DNA is

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replicated once and is divided twice reducing the number of chromosomes by half.

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MEIOSIS – Human diploid number

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46

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MEIOSIS - In humans the haploid number is

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23

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MEIOSIS - Forms

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gametes

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MEIOSIS - Occurs in

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the reproductive structures:

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MEIOSIS – the reproductive structures of Plants is

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Anthers - Male, Ovules – Female

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MEIOSIS – the reproductive structures of Animals is

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Testes – males, Ovaries - females

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MEIOSIS – Why is it important to create haploid chromosomes in Meiosis

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reducing the chromosomes in half is Important so that when the two sex cells fuse during fertilization to form a zygote the diploid chromosome number can be restored.

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MEIOSIS – What is a zygote

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(first fertilized egg cell) Egg (23) + Sperm (23) → Zygote (46)

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MEIOSIS – Since different gametes combine during fertilization

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fertilization contributes to genetic variation

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MEIOSIS – Meiosis occurs in two different divisions

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Meiosis 1 and Meiosis 2

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MEIOSIS – Occurs from one

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mother cell, the end product is 4 haploid cells

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MEIOSIS – Prior to meiosis I, DNA is replicated

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forming two sister chromatids for each chromosome.

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MEIOSIS – Meiosis I is called the

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Reduction Division

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MEIOSIS I – What happens in Prophase I of Meiosis 1

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DNA condenses, Homologous chromosomes pair up, Crossing over occurs, Nuclear membrane breaks down, Spindle fibers attach to kinetochores, Pairs of centrioles move to opposite poles

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MEIOSIS I – This process is called synapsis

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when homologous chromosomes pair up.

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MEIOSIS I – Paired homologous duplicated chromosomes are referred to as

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tetrads

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MEIOSIS I – Crossing over is

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Non sister chromatids cross over and exchange genetic information.

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MEIOSIS I – Because of crossing-over, the genetic instructions from a father and a mother are

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mixed and the daughter cell receives chromosomes with recombined genes.

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MEIOSIS I – What happens Metaphase I of Meiosis 1

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Homologous pairs are aligned in the middle of the cell in a completely random manner

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MEIOSIS I – When the chromosomes line up on the equator in a completely random manner it is called the

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Law of Independent Assortment

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MEIOSIS I – Contributors to variability

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crossing over, fertilization, and the Law of Independent Assortment

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MEIOSIS I – What happens during Anaphase I of Meiosis 1

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Homologous chromosomes separate and move towards the poles. Sister chromatids remain attached.

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MEIOSIS I– What happens during Telophase I of Meiosis 1

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Chromosomes reach the poles, A nuclear envelope forms around each set, Spindle fibers breakdown. DNA decondenses. Cytokinesis begins

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MEIOSIS I – The end result is the chromosomes are

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haploid (1n) because each contains 1 set of duplicated chromosomes. In spite of having 46 chromosomes – they are considered haploid due to the fact that the set is mixed and no longer identical

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INTERKINESIS – is

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Period between meiosis I and meiosis II.

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INTERKINESIS – DNA synthesis

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does not occur

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INTERKINESIS – Centrioles are

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duplicated.

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MEIOSIS II - is

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Equatorial Division

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MEIOSIS II – What happens in Prophase II of Meiosis II

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Chromosomes condense, Nuclear envelope and nucleoli breakdown, Spindle fibers attach to the kinetochores and centrioles migrate to opposite poles.

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MEIOSIS II – Does crossing over occur in MII PII

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Crossing over does not occur

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MEIOSIS II – What happens in Metaphase II of MII

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Duplicated chromosomes randomly line up at the equator

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MEIOSIS II – What happens in Anaphase II of MII

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sister chromatids separate to become independent chromosomes and migrate to the poles.

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MEIOSIS II – What happens in Telophase II of MII

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Chromosomes reach the opposite poles, A new nuclear envelope and nucleoli form, Spindle apparatus breakdown, Chromosomes decondense, Cytokinesis begins

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MEIOSIS II - The end result is

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4 haploid cells

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SPERMATOGENESIS - Occurs in

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the testes

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SPERMATOGENESIS - Begins with

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spermatogonium which are the diploid mother cells.

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SPERMATOGENESIS - The spermatogonia divide to produce

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diploid primary spermatocytes

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SPERMATOGENESIS - Two secondary spermatocytes form from

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the primary spermatocytes. The secondary spermatocytes are haploid (each with 23 duplicated chromosomes).

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SPERMATOGENESIS - The secondary spermatocytes divide to produce

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four spermatids each with 23 chromosomes.

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SPERMATOGENESIS - Spermatids then mature into

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motile sperm

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Oogenesis - Occurs in

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the ovaries

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Oogenesis - Unlike the four sperm produced from a single primary spermatocyte, only 1 ovum

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is generated from each primary oocyte.

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Oogenesis - The oogonium is

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the diploid mother cell.

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Oogenesis - The oogonium divides to make

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1 diploid primary oocytes. Before, birth meiosis I is stopped.

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Oogenesis - Right before ovulation, meiosis I is resumed and the primary oocytes

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divide to make haploid – secondary oocytes.

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Oogenesis - During this division, one of the primary oocytes receives

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the cytoplasm, while the other primary oocyte becomes a polar body (first polar body). The polar body is discarded and disintegrates.

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Oogenesis - Division of the secondary oocyte is stopped until

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fertilization.

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Oogenesis - If fertilization does not occur, meiosis II

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never finishes its division. Oogenesis - If fertilization occurs, meiosis II is completed

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Oogenesis - As with primary oocytes, one of the cells receives

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the cytoplasm and the other doesn’t, resulting in a second polar body

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Mitosis VS Meiosis - Occurs in somatic

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mitosis

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Mitosis VS Meiosis - Produces two diploid daughter cells

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Mitosis

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Mitosis VS Meiosis - Each cell is identical to the parent cell.

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Mitosis

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Mitosis VS Meiosis - Involves only 1 division.

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Mitosis

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Mitosis VS Meiosis - Occurs in gametes

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Meioisis

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Mitosis VS Meiosis - Produces 4 haploid cells

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Meiosis

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Mitosis VS Meiosis - The haploid cells are different from the mother cells because of crossing over and the law of independent segregation.

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Meiosis

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Mitosis VS Meiosis - Involves 2 divisions.

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Meiosis

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Two types of cell division

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1) Mitosis and Binary Fission 2) Meiosis

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Mitosis and Binary Fission- results in

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exact duplication of parent cell (2N to 2N)

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Meiosis - results in

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production of gametes (2N to 1N)

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Mitosis - Functions

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a) cell reproduction b) replacement of cells c) healing d) growth e) regeneration (in some organisms)

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Mitosis – Phases

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a) Cell cycle b) S phase c) Prophase d) Metaphase e) Anaphase f) Telophase h) Cytokinesis

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Cell cycle

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cell division, G1, S phase, Mitosis, G2

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S phase

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duplication of chromosomes, sister chromatids bound by centromere

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Prophase

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appearance of chromosomes

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Metaphase

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lining up along the equator

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Anaphase

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splitting of the chromosomes

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Telophase

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segregation, cell plate appears in plants differs between plants and animals

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Cytokinesis

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splitting of cytoplasm - not part of mitosis in animals

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Meiosis – Function

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sexual reproduction

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Meiosis sexual reproduction results

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diploid (2N) adult produce gametes (sperm, eggs = haploid - 1N)

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Meiosis characteristics

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2 two cell divisions in order to produce haploid gametes

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Meiosis is restricted to

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gonads

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Meiosis I Phases:

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prophase I, metaphase I, anaphase I, telophase I

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MI metaphase I what happens

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homologous pairs line up across the equator from each other

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MI anaphase I what happens

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homologous pairs are split (reduction of chromosomes = 2N - 1N condition)

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Meiosis II Phases:

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prophase II, metaphase II, anaphase II, telophase II

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MII - metaphase II what happens

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chromosomes line up along the equator like they were going through a mitotic division

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MII anaphase II what happens

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chromatids are split by breaking the centromere (in animal cells)