Biology Year 10

Cells structures and Organelles

What are cells?

The building blocks of life

How does each cell know what to do?

DNA tells the cells what proteins to make

Characteristics of cells

Plasma membrane

Cytoplasm

DNA

Ribosomes

DNA

Genetic material

Ribosomes

Synthesize proteins

Prokaryotes

• No nucleus

• No organelles

• single cell

• DNA

• cell

• membrane

Eukaryotes

• Nucleus

• Multicellular

• Organelles

• DNA

• Cell

• membrane

Organelles in animal cells———

Cell membrane

•       – Selectively controls what enters and leaves the cell; provides protection and support.

Golgi apparatus

Packages proteins transport inside and outside the cell.

Centrosome

Essential for proper cell division.

Vacuole

•       Stores water, nutrients, and waste products

Mitochondrion

Generates energy (ATP) through cellular respiration

Nucleus

Stores genetic material (DNA) and controls all cell activities

Smooth endoplasmic reticulum (SER)

Synthesizes lipids

Lysosome

Contains digestive enzymes to break down waste materials

Cytoplasm

Jelly-like fluid that fills the cell.

Rough endoplasmic reticulum (RER)

Covered in ribosomes; synthesizes and transports proteins.

Ribosome

Builds proteins from amino acids

Nucleolus

Produces ribosomes inside the nucleus.

Nuclear membrane

Surrounds the nucleus, controlling movement of molecules in and out.

What is DNA

•Molecule that contains genetic information for the development and functioning of an organism

DNA structure

The DNA molecule consists of two strands that wind around one another to form a shape known as a double helix. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases--adenine (A), cytosine (C), guanine (G), and thymine (T)

The sequence of the bases along the backbones

serves as instructions for assembling protein and RNA molecules

DNA sequences control

protein production

Mutations

Occur in base sequence and can alter cell function

Genetic Information

•       DNA stores instructions for growth, development, functioning, and reproduction.

Protein Synthesis

•       DNA codes for proteins via transcription and translation.

Heredity

DNA passes traits from parents to offspring.

Cell Regulation

DNA controls cell activities by regulating gene expression.

Mutation & Evolution

DNA mutations create variation, driving evolution

Cell division

•For an organism to grow, repair and reproduce the cells that make up the organism have to increase in number

How does DNA replicate

DNA replication

1. DNA unwinds

2. Base pairing- DNA polymerase adds new complementary nucleotides

3. Joining-DNA ligase helps seal DNA fragments to form one long strand

DNA — Genes — chromosomes

How can DNA replicate

•For DNA to be easily replicated or undergo transcription, the DNA needs to be stored inside the nucleus in an organised way

Chromosomes

Genes

Mitosis

Importance of Mitosis

Somatic Cells

•Body cells that contain the normal number of chromosomes

Skin cells, brain cells, bone cells etc.

Chromosome number: contain two copies of each chromosome

Gametes

Chromosome number: contain one copy of each chromosome

Fertilisation

Fertilisation is the joining of a sperm and ovum (egg cell) it results in the formation of a zygote (fertilised egg)

Meiosis

Meiosis vs Mitosis

Prokaryotes

Before nucleus (bacteria)

Eukaryotes

true nucleus (animal and plant cells)

ribose

sugar

nucleic

nucleotides (buildings)

Phosphate backbone

What determines genetic traits

the sequences of bases

Gene

makes protein that builds the wall in a mitochondria

Cell division

for an organism to grow, repair and reproduce, each cell copies itself

Why is process of replication important?

Mitosis steps 

Interphase- DNA duplication before mitosis (genetic material is being duplicated)

Prophase- before (getting ready to make the split) 1 allele for brown hair one for blonde

Metaphase- the chromosomes line up in the middle of the cell (pulled in by centrioles and the spindle fibres are like ropes)

Anaphase- chromosomes move to opposite sides of the cells (spindles help move chromosomes to the two ends)

Telophase- Chromosomes are  at the complete opposite ends, so two nuclei (each side 46 chromosomes)

Cytokinesis occurs after mitosis (separates the cell into two creating two identical daughter cells) organelles of the cell have also been seperated (mitochondria)

Condensed DNA creates

Chromosomes, which are made of proteins and DNA

Chromosomes are kept together by

centromeres

Meiosis

Prophase 1: Crossing over (they transfer genetic information)

Metaphase 1: Middle, the chromosomes will line up in the middle of the cell in pairs

Anaphase 1: pulled away by spindle fibres

Telophase: Two cells

Prophase 2:

Metaphase 2: they are in  single line

Anaphase 2: away

Telophase 2: split the cytoplasm

 

Relationship between DNA, Chromosomes and Genes

DNA is the molecule that carries genetic information. it coils around proteins to form chromosomes Genes are sections of DNA on chromosomes that code for specific traits.

DNA

• Double Stranded

• Bases A, T, C, G

• Sugar: Deoxyribose

• Function: stores genetic information

• Location: DNA

RNA

• Single stranded

• Bases: A, U, C, G

• Sugare: RIbose

• Function: carries genetic information from DNA to ribosomes for protein synthesis

• Locations: nucleus and cytoplasm

Asexual Reproduction 

Crossing Over

Random Fusion of gametes

Maternal Allels come from…

mothers egg

Paternal Allelel

Fathers Sperm

Maternal and Paternal Allele

come together during fertilisation to form offspring genotype

Karyotypes

Homologous Chromosomes

Allele

Different forms of the same gene

Genotype

the combination of alleles that a person has in their DNA

Phenotype

the physical expression of a genotype

Homozygous

Having identical alleles for a gene

Heterozygous

Having two different alleles for a gene

Hemizygous

Having only one allele for a gene instead of wo (e.g. males in X-linked genes)

4 types of bases

how many chromosomes found in each autosomal (body) human cell

Natural Selection

Spontaneous mutations

Gene FLow

Covergent evolution

Reproductive isolation can occur through…

Geographical isolation

Vestigial structures

Comparative DNA sequencing 

Asexual

Mitosis

sexual

Meiosis (different from parent, think about mice and their colours)

Types of Asexual reproduction

+Budding- bud and parent are IDENTICAL

+Binary fission- •Cell divides into two identical daughter cells

•Unicellular organisms (bacteria, protists

+Vegetative propagation- taking a part of a plant makes a new plant

+Fragmentation- •Single parent breaks into parts that regenerate into whole new individuals.

•Flatworms

Advantages and Disadvantages of Asexual reproduction

QUICK AND ENERGY EFFICENT AND large amounts of offsping produced DISADVANTAGES LIMITED VARIATION MEANING POPULATION IS VULNERABLE TO CHANGES IN THE ENVIRONMENT OR TO DISEASE (DON’T HAVE THE GENE THAT WILL HELP THEM SURVIVE)  

Offspring is the result of sexual reproduction

Gametes and Meiosis

Sexual reproduction pros and cons

SEXUAL REPRODUCTION PRO: VARIATION AND ADAPTATION

CONS: TAKES TIME (INTENSIVE) AND ENERGY

+NEED TO FIND A MATE

Asexual

sexual