1. The Organism and the Cell
Chapter 2

2. Cells Eukaryotes are organisms with DNA in the nucleus
Prokaryotes lack a nucleus to enclose DNA

3. Basic Body Plan
We are similar to animals we share a common ancestry with
Cells- fundamental units of life
Cells are organized into tissues, which form organs, which function together in organ systems, which make up an organism

4. Cells
Each cell in a body has a full set of genetic information that directs growth, development, and metabolism
Cells are held within a membrane. In eukaryotes a nucleus separates the genetic material from the cytoplasm, which houses organelles, which have various functions.
Page 19 has a full list of all organelles and their functions

6. Classes of Cells
Somatic cells: thousands of types of cells making up our body structure
Gametes: sex cells (egg or sperm)
Important!!

7. Cell Development
All of the cells in an individual are derived from the fertilized egg, the zygote
half of the information in the zygote comes from the mother and half from the father
Right after fertilization the zygote divides into 2 cells, which then begin the process of differentiation, meaning they grow in different ways
These then develop into organs, musculoskeleton system, nervous system

8. Cell Development
The process of cell division with somatic cells is called mitosis
The process of cell division with gametes is meiosis (Chapter 4)

9. Chromosomes Most genetic material is found in the cell’s nucleus
Nuclear DNA is packaged into chromosomes
Chromosomes have arms, centromeres and sister chromatids, seen on page 21
The number of chromosomes is species specific
The normal number for a human is 46

11. Chromosomes in Humans The number 46 refers only to somatic cells
This number is the diploid number (full number)
In gametes, the number of chromosomes is 23…why?
This is the haploid number (half number)

12. Chromosomes in Humans The number 46 refers only to somatic cells
This number is the diploid number (full number)
In gametes, the number of chromosomes is 23…why?
This is the haploid number (half number)
You can only pass down half of your genetic information to a child. Half also comes from the other parent

13. Chromosomes in Humans
The 23 pairs of chromosomes are lined up according to their size, called a karyotype. They also have different banding patterns
Each chromosome is in a pair, which is called homologous.
This means that the genes are found at the same location on each pair
The 23rd pair are the sex chromosomes, X or Y
Look at page 22. label the chromosomes 1-23

14. What makes a pair of chromosomes homologous is where each gene is found on the chromosome

15. Homologous Chromosomes
A gene is a segment of DNA that codes for a specific function or trait in the body
The position a gene occupies on a chromosome is called the locus
Two chromosomes are homologous when the genes at a given locus code for the same trait on both chromosomes.
Remember, different versions of genes are called alleles

16. Homologous Chromosomes

17. Chromosomes can be identified by
size
position of the centromere
banding pattern
LONG
MEDIUM
SHORT
VERY SHORT
CENTER
AWAY FROM CENTER
AT OR NEAR THE END

18. Chromosome Groups Group A: Very long, centromere in center (1-3)
Group B: Long, centromere away from center (4-5)
Group C: Medium, centromere away from center (6-12)
Group D: Medium, centromere at or near the end (13-15)
Group E : Short, centromere away from center (16-18)
Group F: Short, centromere in center (19-20)
Group G: very short, centromere at or near the end (21-22)

19. Chromosomal Abnormalities
Error in cell division: usually in meiosis
Structural Modifications
Cat Cry Syndrome deletion of part of Chromosome 5
infants cry like a cat
14/21Translocation Carrier, Chromosomes are connected
has Down Syndrome-like characteristics
Fragile X: long arm of the X chromosome is loose or has broken off
Shorter than average
Large heads with long, narrow faces and large ears

20. Irregular number Trisomy 21 XO Turner XXY Klinefelter
Down’s Syndrome
XO Turner
Short, Webbed necks, sterile females
Most fetuses die before birth
XXY Klinefelter
High-pitched voice, reduced fertility, some mental impairment
XXX Superfemale (metafemale)
Taller, normal development, fertile
XYY Supermale (metamale)
Tall, high testosterone levels, Fertile
predisposed to antisocial behavior?

21. Assignment Each group will complete two labs/Dived the group in two
Group 1: complete the lab starting on page 25
Group 2: Grab a Mystery Packet
Self-Test 2.1
Additional Self-Test, pg are good study questions (but not turned in)