chapter 6 chromosomes & cell reproduction
DESCRIPTION
Chapter 6 Chromosomes & Cell Reproduction. General Information. about 2 TRILLION cells are produced by an adult human body EVERY DAY. new cells are formed when old cells divide. cell division = cell reproduction. Examples: a cut that is healing, a fawn growing. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/1.jpg)
Chapter 6Chromosomes & Cell Reproduction
![Page 2: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/2.jpg)
General Information
about 2 TRILLION cells are produced by an adult human body EVERY DAY new cells are formed when old cells divide cell division = cell reproduction
Examples: a cut that is healing, a fawn growing
![Page 3: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/3.jpg)
Prokaryotic Cell Reproductiono asexual reproduction that produces identical offspringo Binary Fissiono two stages:
1. DNA is copied (so each copy with have genetic information
2. cell divides
![Page 4: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/4.jpg)
Eukaryotic Cell ReproductionGene – a segment of DNA that codes for a protein or RNA molecule; determines how a person’s body develops and functions
Chromosome – DNA and proteins associated with DNA
![Page 5: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/5.jpg)
As a cell prepares to divide…1. Chromosomes become
visible2. DNA is copied3. It coils up
![Page 6: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/6.jpg)
Chromosome Parts:• Chromatids – two exact copies of DNA that make up each
chromosome• Centromere – the region of the chromsome that holds the two
sister chromatids together during mitosis
![Page 7: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/7.jpg)
Human Chromosome Labeled:
Chromatid
Chromatid
Centromere
![Page 8: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/8.jpg)
Chromatids are separated and one goes into each new cell, ensuring that each new cell will have the same genetics information as the original
![Page 9: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/9.jpg)
How many chromosomes do humans have?23 sets (pairs) of chromosomes -> 46 chromosomes total
Homologous chromosomes (homologues) = chromosomes similar in size, shape, & genetic content
• You have 23 pairs of homologous chromosomes, one of the homologues in each pair is from your mother and one is from your father
• Think: who do I look like?
![Page 10: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/10.jpg)
Species have different diploid numbers
![Page 11: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/11.jpg)
Important Terms• When a cell contains two sets of chromosomes (one set of 23 from the individual’s mother and a second set of 23 from the individual’s father), we call these cells diploid cells• “di” means two• Cells that only contain one set of chromosomes (23) are called haploid cells• “ha” can start off the word half (or half the number of
chromosomes)• Somatic cells are all the cells in the body other than gametes• Gametes are reproductive cells; ex. Sperm cell, egg cell
![Page 12: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/12.jpg)
![Page 13: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/13.jpg)
n = 23 chromosomes
(23) (23) 2(23) = 46
haploid + haploid diploid=
Fertilization = fusion of 2 haploid gametes; forms a diploid
![Page 14: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/14.jpg)
Fertilization• A fertilized egg is called a zygote, it’s the first cell of
a new individual
![Page 15: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/15.jpg)
Of the 23 pairs of chromosomes in humans:
• 22 pairs (or 44 chromosomes) are autosomes, or chromosomes that are not directly involved in determining the gender of an individual
• 1 pair (or 2 chromosomes) contain genes that will determine the sex of the individual and these are called sex chromosomes (usually referred to as X & Y chromosomes)XX = Female XY = Male
![Page 16: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/16.jpg)
Would this be a boy or girl?
![Page 17: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/17.jpg)
The structure and number of sex chromosomes vary in different organisms.
• Some insects (grasshoppers) no Y so O stands for absence of chromosome • female is XX• male is XO• In birds, moths, & butterflies• males have XX and females are X
![Page 18: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/18.jpg)
Karyotype• A photo of the
chromosomes in a dividing cell that shows the chromosomes arranged by size
• Can alert that there is an abnormality in an individual…why?
![Page 19: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/19.jpg)
The presence of all 46 chromosomes is essential for normal development and functionTrisomy – humans with more than 2 copies of a chromosome will not develop properly
Polydactyly
Down syndrome = condition with extra copy of chromosome 21 (trisomy 21)
![Page 20: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/20.jpg)
How does this happen?
1. All the egg cells in a female are present at birth, she will never make more. Males, on the other hand, produce new sperm throughout their adult lives.
Therefore, as a female gets older her eggs accumulate damage.
2. Mutations can occur.
Doctors are able to perform prenatal testing to check for certain genetic disorders.
![Page 21: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/21.jpg)
Mutations = changes in an organisms’ structures
Four types of mutations:1. Deletion – piece of chromosome breaks off
completely; new cell will lack a certain set of genes; usually proves fatal to zygote
2. Duplication – a chromosome fragment that attaches to its homologous chromosomes; carries 2 copies of a certain gene
3. Inversion – a chromosome piece reattaches to the original chromosome but in a reverse orientation
4. Translocation – if a chromosome piece reattaches to a non-homologous chromosome
![Page 22: Chapter 6 Chromosomes & Cell Reproduction](https://reader036.vdocuments.mx/reader036/viewer/2022062305/568166c5550346895ddad3ac/html5/thumbnails/22.jpg)
Deletion – piece of chromosome breaks off completely
Duplication – chromosome fragment attaches to its homologous chromosome
Inversion – chromosome piece reattaches to the original chromosome but in reverse orientation
Translocation – piece reattaches to a non-homologous chromosome