Chap. 20 The Role of Genes in Inheritance Grade 8 Science Mrs. Barr/ Mrs. Batten
Transcript
Slide 1
Slide 2
Why is it important for organisms to reproduce?(30s) so they
can pass on hereditary material so they can continue the
species
Slide 3
Is a chemical Made of 2 long strands Each strand has a sugar, a
phosphate and a nitrogen base (adenine, thymine, cytosine and
guanine Is found in cells In chromosomes Controls the production of
proteins
Slide 4
Is like a blueprint of a house stores and uses information to
direct the activities of the cell & to make exact copies of
itself Shaped like a twisted ladder
Slide 5
Mitosis is when the nucleus divides 2 new nuclei are made
Slide 6
What causes a cell to divide? Some cell biologists have
observed that size is a trigger As a cell grows, its surface area
grows slower than its volume. The Cell Cycle Sequence of events
that occur in a cell from mitosis to mitosis Although there are
names for these steps, it is a continuous process
Slide 7
Interphase The largest part of the cell cycle This time
variesex. Yeast cell could be 2hrs, an amoeba a few days, animal in
early embryo stage could be every 15-20 min. When the cell is
growing in volume Duplicates DNA Mitosis Prophase Nuclear membrane
disappears Chromosomes become visible
Slide 8
Metaphase Chromosomes line up in the center Anaphase Chromatids
of each chromosome separate Telophase New nuclear membrane forms
Cell starts to pinch Cytokinesis Cytoplasm of the original cell
splits
Slide 9
How does one organism reproduce? Its called A- sexual
Slide 10
Binary Fission When the parent organism splits to form 2 new
organisms Budding Happens in both unicellular and multicellular
organisms Organism develops buds on its body and when that bud
reaches a certain size it separates Regeneration Regrowth of a
missing or damaged body part
Slide 11
Cloning organism has same DNA as parent
Slide 12
How come you wake up in the morning feeling fine and feel awful
by the end of the day? Bacteria reproduce through binary fission
and can reproduce in as quickly as 30 minutes
Slide 13
Sexual Reproduction New organism comes from DNA of 2 cells
Spermegg new organism
Slide 14
A body cell has 46 chromosomes (23 pairs) A sex cell has only
23 chromosomes
Slide 15
Meiosis special kind of cell division Two nuclear division
Produces haploid cells Takes place only in reproductive
tissues
Slide 16
Meiosis has phases just like Mitosis Meiosis I Prophase I,
Metaphase I, Anaphase I, Telophase I & Cytokinesis Meiosis II
occurs in each of the cells produced by Meosis I, is not preceded
by DNA replication Prophase II, Metaphase II, Anaphase II,
Telophase II, & Cytokinesis
Slide 17
Fertilization The fusion of gametes (haploid cells) to form a
diploid cell This recombination allows for variation 23 46
Slide 18
When an individual is missing either a chromosome from a pair
(monosomy) or has more than two chromosomes of a pair (trisomy). An
example of a condition caused by numerical abnormalities is Down
Syndrome, also known as Trisomy 21 (an individual with Down
Syndrome has three copies of chromosome 21, rather than two).
Turner Syndrome is an example of monosomy, where the individual -
in this case a female - is born with only one sex chromosome, an
X.
Slide 19
Plants can reproduce sexually! Female reproductive organ
produces eggs (ovary ), and male produces sperm (pollen) Some
plants are either male or female Plants rely on birds, bees, wind
and water to move their egg and sperm to other plants
Slide 20
How many chromosomes does a body cell have? How many
chromosomes does a sex cell have? What is it called when sex cells
are formed?